update time in a score

There's something very strange going on here.

Can you attach the original XML?

Gunnar,

I strongly suspect that this is closely related to another bug in Musescore (see http://musescore.org/en/node/15169 for some additional information). For some reason, changing time signatures must be very complicated and apparently the developers are in fact working on this issue. In the mean time, what I can tell you is that editing "damaged" measures is not easy (if possible at all). As you've already discovered, dropping a 4/4 signature on the first measure does nothing. The only solution I've found is to delete the faulty measures, re-insert empty ones and move on from there.

I've had a look at your score and noticed that the first measure has a mismatch between the "actual" (3/4) and "nominal" (4/4) time signatures. All remaining measures are OK (nominal=actual=4/4). I tried a simple repair (i.e., changing the "actual" settings to 4/4) and it didn't work. In fact it crashed the program. On the other hand, if I delete the first measure, then the remaining measures now are still all 4/4. Then simply inserting a new first measure (with Create...Insert One Measure) fixes the problem.

In your case, since the first measure is empty anyway, that's all there is to it. If you had any notes in the first measure, then you would either have to re-enter them or move them to an empty measure further on in the score, finally moving them back once the first measure is fixed.

OS and mscore info:
Linux mint 12; mscore 2.0.0 unstable from svn: r5516