Problems with measures format
I need to make my score 8 measure for each exercise like in the picture below. I'm having this problem with most of my scores, after a number of bars, musescore breaks system and I can't have a full control of it. I let you the image below so you can understand what I want to do. I tried many ways and I can't have the 8 measure per line I want (See bar 23-24) 
Comments
These measures are just to busy to fit into one system, at the current settings for page width and scaling as well as stretch and a bunch more.
You have control over where breaks are, that's what the Breaks & Spacers palette is for, or the shortcut Enter. But, true, it can't break the laws of physics, and those last eight measure have too many notes to actually fit given your current settings for staff size, page size, minimum note distance, etc. So you'll need to change one or more of the relevant settings. Once you figure out which settings you are willing to compromise, MuseScore will happily oblige.
If you need further assistance, please attach the actual score rather than just a picture, then we can make more specific suggestions.