> I wonder if there is a music notation woftware which allows you to just enter all the notes first, then you can go back and edit the duration

MuseScore supports the reverse of that workflow - you can enter the durations of notes and rests initially, then go back and "repitch" the notes in a second pass.

I remember many years ago using a Windows scorewriter (possibly this one? https://en.wikipedia.org/wiki/NoteWorthy_Composer) which placed notes into bars itself, based on their duration. If you went back and deleted, inserted or modified a note, the whole score would then reflow accordingly, much like wordwrap in a word processor.