Positioning of elements

I installed MuseScore4 then opened a file I had made in MuseScore3 and opened all the parts.
In the parts the margin to the right of the title block looked small. At the start of the music I had inserted "Moderato" followed by "crotchet=144" and positioned the latter to the right of the former in MuseScore3. In MuseScore4 they overlapped so I started going through the parts and repositioning "crotchet=144". I also adjusted bar sizes where, for example, there were only 2 or 3 bars on the last line or in some parts the last line was short. (I had already tidied all this up in MuseScore3). After I had done a few MuseScore4 just disappeared. I double clicked on the icon on the desktop and it started again with the message that it had stopped unexpectedly, would I like to restore the previous session. Yes. The file opened and the title block was nicely positioned with correct margins. There was now too big a gap between "Moderato" and "crotchet=144" in the parts I had altered and just the right gap in those I hadn't.
I closed without saving and started all over again and exactly the same things happened.