When working with a score there are a few extra things to take into account, especially if some parts have been made invisible in a score. Take the example 'rhumba' for example.
In addition to the two visible parts, there are three others, a bass part, a drum part and an automatically generated chord part. The latter usually does not cause any problems because it is always recreated from the main part. Let's first make all parts visible in the score.
The last measures will then look like above. The cursor is in the top bar after the ending barline. In the bottom bar, the drum part, the last two of three unattached eighth rests should be replaced by a quarter rest. First with <Tab> three times to the bottom bar, and then with <> to the second rest. Verify that the insert mode button is off. Doubling the duration with <F8> or replaces both eighths with a quarter.
What if insert mode had been on? In that case, the existing 1/8 would have been doubled to a quarter and an eighth note would have been added to the lower part:
The eighth rest has now moved to the last bar where there is now an eighth note too much... The score is no longer in sync and anything after that bar can cause all sorts of unexpected problems. Since it is the last measure, it will remain with an error message from MusiCAD as soon as the notation bar is exited:
The main melody is shorter than the drum part and MusiCAD will notify you. Click 'ok' and MusiCAD puts you in the problem-causing measure. MusiCAD tries to solve the problem situation by giving the other parts even an extra eighth (grayed out) of rest
Use <Delete> to remove the problem-causing rest in the 4th part; the score is synchronous again, and MusiCAD cleans up the extra rests in the other parts of its own accord.
Sometimes it is necessary/useful to temporarily create an incorrect score in insert mode, which you can correct afterwards. In overwrite mode you will see that some operations are impossible precisely because they would cause an out-of-sync score.