Can't change time signature for the whole song

I forgot to change the time signature from 4/4 to 3/4. Now I tried to chance the time signature at the beginning of the songs. Only the first couple of bars change to 3/4. The rest remains in 4/4.

What am I doing wrong.

These are the things, that drive me crazy in Dorico.

Best Regards

Ingo

Is there as hidden time signature (or even a barline change) at the point where the transformation to 3/4 stops?

(Viewing signposts may be your friend here.)

If you ensure that View > Signposts > Time Signatures is ticked (and the toggle at the top of that menu isn’t set to Hide All Signposts), are there any red time signature signposts showing above the third bar of the song? If so, you have a hidden time signature you need to remove - try selecting and deleting the barline that immediately precedes the signpost.