[itsme]

I recommend that you first increment the staff space (sp) (Format - Page Settings... - Scaling) as desired. Then remove existing line breaks (Format - Add/Remove System Breaks - Remove current system breaks). If you don't like the resulting automatic system breaks and page breaks set them as you like via Add/Remove System Breaks or via drag&drop from the "Breaks & Spacers" palette.

For further questions just search or ask in the MuseScore forum https://musescore.org/de/forum. You can find many competent, helpful and patient guys there that answer your questions in English and German.