Shalom everyone

I have a question I'm arranging an orchestra for guy and I did it in 4/4 but he said he wants the C theme to be 3/4. So I change the time signature to 3/4. Now the melody and all the other instruments look messed up. I tried to change the note duration before and after changing the time signature but that did not work.Is there way I can change the signature without messing up to much? Thanks

Finale 2014.5

windows 10

Have nice week

Marcus