Adding rests and notes according to timesignature does not fit

Hello! I am new to the program, used finale before. Problem: when I inserted a measure and try to do notes and measures it does not want to accept the correct timesignature in this case 4/2. All of a sudden the cursator jumps to next measure having done only 2/2. Are some icons activated, that shouldn't? Grateful for advise.
I have just signed up for the onlineteaching!
Eva