Printing
When I started this project, the print command was default US letter (8.5 X 11). Two days ago the default changed to A4 so now I loose the bottom portion of my score. I can change it manually each time (format/page settings) but I want the US letter format as a default - not A4 . What caused this? How do I change the default back to US letter format.
Comments
See: https://musescore.org/en/node/316919 (https://musescore.org/en/node/316919#comment-1059660 )
HTH
What do you mean by "this project" and "default"/ Once you choose a page size for a score, it stays that way, and defaults have nothing to do with it. The default is the size chosen for a new score. So if your system defaults to A4, and you created a score, it will start out A4. if you changed it to Letter, that's fine for that score and it will remain that way, but the next score will come out A4 again.
The default page size comes from the settings for default printer, so be sure it's the way you want. On Linux, this mechanism doesn't work. so instead consider setting the attached MSS files as your defaults in Edit / Preferences / Score.