Why when I push back a face it disappears? like in the video
The term you are looking for is “clipping”. A forum search will produce many results. Study them to get the answer as to how to prevent it.
@RLGL … I’m not so sure @marceltanure is talking about clipping. If he is having trouble with pushing the front section of the text without losing it, length snapping could be one problem. There may be other reasons, but that was the first that came to mind.
It is happening again, I didn’t put any certain measurement I m just trying to snap it, see:
Its not that, see the video in my last answer
Post the model so someone can look at it.