I have tried numerous ways to insert a beat rest in an existing measure that pushes everything over and it does not respond. What I have done is insert a note and then delete it with the backspace and that creates the beat rest. Is that the only way?
Invoke caret.
Type I to turn on Insert mode
Type , to turn on Rest input
Type 6 for a quarter/crotchet (assuming that’s how long the “beat” you want is - you haven’t told us)
Type Y (or any letter from A-G) to type a rest.
Remember to turn off Insert mode and Rest mode when you’re done.
Since I turned off mouse entry, I discovered that I can insert a rest by doing what you said but on the fourth step, I just hit any note on my midi keyboard and, voila, a rest shows up. How cool is that?
Another way is to lengthen a note in insert mode (to push the rest of the score to the right) and then shorten it in overwrite mode.
For example if you want to insert a quarter rest after a quarter note, select the note and press I 7 I 6 (those are the letter I for insert mode, not the digit 1).
That’s the same number of key strokes as pianoleo’s method, but it might be faster to type.