Yes. measures 1-80 are in 4/4. I want to change measure 41 to 5/4, leaving 42-80 in 4/4. Then changing m41 to 5/4. The eighth note divisions above the 5/4 measure are ‘iiiiIiii’ rather than the expected ‘IiIiIiIiIi’ and the 5/4 measure shows 2 quarter rests and a half rest.
Place the entry caret where you wish to add the extra beat in the 5/4 measure. Then type SHIFT + B + 1q. That will add one quarter rest to the measure, which you can then replace with whatever you wanted to add in that beat.
Are you referring to the subdivisions of the measure when the caret is on beat one? With the 5/4 measure, you could also enter it as something like 3+2/4 if that is how you want the measure to subdivide.
You could use Insert Mode’s 4th submode (Global adjustment of current bar), and either insert notes or change the value of the existing ones: it will automatically create a new time signature according to what you add, and restore the 4/4 in the next bar, without moving anything before or after your 5/4: