Hello everyone!
I have Prime 4+ and Engine DJ 4.0.0. I did some research on the community group and on the internet but I didn’t find any answer to my problem 
In fact, I would like to know if it is possible to lock the cue? I explain myself:
This is normal (don’t know why) if you want to return to the beginning of the song (not the first beat) hold shift then press cue. My advice is set a hot cue at the beginning of the first beat then when you press the hot cue button it will return to the beginning (or wherever you placed the hot cue) bare in mind the hot cue will automatically play the track (default setting) there’s a toggle in the settings to prevent this (can’t remember what it’s called)
This is how I have mine set up, if I press the hot cue it returns to the start of the hot cue position but doesn’t play unless I hold it, if you want it to play press play while holding the hot cue to perform a cue play takeover (hope that makes sense) or just press play when at the start.
Or alternatively make sure the track is playing when you press the temp cue button. It’s a habit you get into after a while.
I admit that the solution with the Hot Cue does not suit me too much because if I’m in another mode, Slicer for example, I have to press on Hot Cue then on pad 1. It is not direct.
For the moment, I will settle for the solution of STU-C although I find this operation not at all practical 
I’ll go back to Engine DJ. I’m not convinced that it will lead to anything. We’ll see
In any case, thank you both for your return!
I might be wrong but I think it’s pretty standard behaviour across the board? If the track is paused it’ll set the cue point to where you paused it.
It’s standard Pioneer behavior since the first CDJ’s in 1994, and copied by almost every major brand. Denon had a different CUE/PLAY behavior, which was invented before Pioneer even turned to the DJ market (1992), but somewhere in the nillies even Denon decided to follow Pioneer’s now industry standard CUE/PLAY behavior.
InMusic implemented a feature that saves the floating/temporary CUE point though, but IMHO they didn’t think this through: it’s a floating CUE for a reason, and gets changed as you loop, stop tracks, etc etc. In other software you explicitly set a “load marker”, which isn’t changed by just pressing pause. This is a better implementation. But of course the purists (I know you are @STU-C) don’t mind just setting the CUE point theirselves. For those purists there is a setting where you choose to set the CUE to the tracks starting point when loading, instead of the saved cue…
(p11: https://cdn.inmusicbrands.com/denondj/legacy/dn2000fltd/DN-2000F_LTD_DFU.pdf
Indeed, to set a CUE point you had to pause where you wanted to cue, the hit play, so the deck is playing, then press cue. If you pressed cue on a paused deck, it would return to the know cue point. If you pressed cue on a playing deck, it would set the cue to the last pause point. In retrospect that was very confusing, but it did work, and back in the day, Pioneer’s way of working confused me… getting nostalgic, I played a lot of gigs on these puppies… 
)
I don’t know if it’s standard. I haven’t tried other models. I have a memory of using CDJ100S that had this principle there but I am not sure anymore. It goes back so far!
Anyway, I have a response from the support service. They told me about the same thing you did.
I asked them if it was possible to have this option. I am not convinced that there is an update but that does not try anything has nothing 
If you want a specific feature you can post a feature request. Or better, vote for an existing feature request. Think it through though, I think you can best accomplish what you want by adding a “load marker” functionality, and I believe such a feature request exists. Its pointless to request 2 features which more or less serve the same purpose, but in a different way: they will both get half the votes (because votes per user are limited), and will probably never see light of day
They said exactly the same thing! I will do that, thank you! 
After I wish that this loader marker once defined can not be modified by pressing Cue when the song is stopped. Basically have a Cue locking like for the Beat Grid
Have a look at some other software on the market (demo versions exist). For example in Traktor you have to save a cuepoint, just like hotcue, but then label it as load marker. A load marker in effect is just a special hotcue. That way, whatever you do with the temporary cue wont affect the load marker anymore…
It makes a lot more sense to have this saved with other permanent cue’s than save a temporary cue (see the contradiction, saved vs temporary?)
Each has its own use of the Cue button. Personally, I would just like there is a possibility to be able to block the cue at a chosen place.
Yeah, but once you go into more advanced tricks you’ll notice that a fixed cuepoint is inhibiting sooner or later
That’s your opinion, I don’t see it like that
The solution, and what most of us are doing, is to set the first hot cue on the beat you want to mix in from, that way you can simply hit that and return to that point. Whilst also saving wear and tear on the temporary cue.
I have already answered on this point
“I admit that the solution with the Hot Cue does not suit me too much because if I’m in another mode, Slicer for example, I have to press on Hot Cue then on pad 1. It is not direct.”
The thing is, mixing tracks together you assume that the music is playing on the track you’re cueing (so you can line the tempo up etc), and if it isn’t you will have stopped that track by pressing the cue button to return it back to that point.
Moral of the story, don’t use pause to stop playback, unless you want to pause it to set the cue.
It’s just habits, practise, training, muscle memory, part of DJing.
Sometimes mistakes happen and you press it at the wrong point or press the wrong button, again just part of DJing and what is reduced with experience.
All you’re doing here is describing situations that can be easily avoided by doing the job more and more. Or to put another way, making a mountain out of a molehill.
Is it really necessary to give lessons and impose your way of doing things? I asked a question, I was answered (thank you again). I will see if I submit my improvement proposal and the community will decide. Topic closed.
Not imposing anything, just offering advice from experience, the decision is yours entirely what you want to do.