Music keeps moving

The score 'moves' because with every note you add or change, the program automatically re-paginates the score. This is necessary. If you don't want to see that while you are working, click on the icon in the main toolbar which says 'Page View' and change it to 'Continuous view.' You'll still see some 'movement' but it should be less intrusive.

When you are done, return to 'Page View' to see how the program proposes to layout your score. At that point you can start making manual adjustments to positioning in individual measures to get the page make-up that you want.

Think of it as the equivalent of "word wrap" in a text editor. As you reach the end of one line, the cursor automatically moves to the next, and with it so does the word you were in the middle of typing. We're used to this with text but for whatever reason sometimes it surprises us at first when the same thing happens with music.

@DinoSoprano, beyond the Recorder485 suggestion you can simply press 'Left' arrow to return to the previous note