How to change staff distances and alignmenta
There's always the same problem when I start a new project, transcription, arrangement or composition: Measure sizes, alignment and staves distances. So I'll show you the problem maybe you can get a better idea where my frustration comes. If you check the image below, the last page has 3 system staves that i had to align manually with a frame. I'm not happy with the result but I'm satisfied for now, what really annoys me is the distance between the vocal staff and the treble staff. It's so huge! Just look at the 3rd staff, the distance between lyrics and the right hand in piano staff. I can't edit this! I tried in many ways or maybe i'm missing something? I hope you can help me because this is driving me crazy everytime I start with a new project. 
Comments
See https://musescore.org/en/handbook/3/layout-and-formatting#style-page and https://musescore.org/en/handbook/3/breaks-and-spacers#spacers
If you attach your actual score instead of just a picture, we can understand and assist better. Generall;y, speaking, though, MuseScore tries to do reasonable things by default if you do give it the chance, by making sure your pages are balanced. That is, if your last page has fewer systems than the others, there's no physical way to make everything the same. So what you should do is going through your score adjusting system and/or page breaks do you don't have so much extra space on the last page, because regardless of where that extra spaces - between staves, above staves, or below them, it's not going to look very professional.
If you can't find a way to avoid an underfill last page, then you can still control how the space is distributed using the settings in Format / Style / Page, You've kind of defeated some of that by inserting frames, first step would be to eliminate those so the settings can do their job. Again, if you attach you actual score, we can advise better.
The reason the space below the local staff is larger than the rest is because a) you have so much extra space on the page, it needs to go somewhere, and b) the default in MuseScore as well as in standard publishing practice is to keep the staves of a grand staff closer together and try to sneak the extra space between other staves and the grand staff, and then also between systems. The controls in the dialog are what affect how much of the extra space goes where. But again, really, the right answer is to plan things to not have so much extra space to distribute, because it's not going to look good no matter what.
All that said, you can also use spacers to add or remove space as needed here and there once you've tweaked the overall distribution of systems across pages and the settings in that dialog to your liking. It's very unlikely to be necessary here though, once you do those first two things.
In reply to If you attach your actual… by Marc Sabatella
I'm sorry to answer until now, i've been busy this week. This is the file so you can see what the problem is I hope it helps! TIA
In reply to I'm sorry to answer until… by MichelCA
See https://musescore.org/en/handbook/3/layout-and-formatting#style-page, "Disable vertical justification of staves", as one option.
In reply to I'm sorry to answer until… by MichelCA
Disabling vertical staves works around a bug that can cause problems in some cases, but it causes other problems like uneven margins on most scores, including this one, so I don't recommend it (only for single-staff scores like lead sheets or parts).
Instead, you should first remove the spurious frames as I suggested earlier, and also the spacers - these interfere with the normal working of the spacing algorithm. Then you simply need to optimize the settings to produce the specific results you want.
But as I said, before, really, it's going to look not very good no matter what settings you choose unless you add breaks to keep the last page from being so out of balance with the others. There's no good reason you should have four systems per page everywhere else and only three here. Whether the extra space is distributed throughout the page (the default) or all bunched up at the bottom, it's not a professional look. The real answer is to avoid having all that extra space to begin with.
In your score, I see a number of systems that look kind of crowded as is, so simply adding some system breaks to relieve the crowding will result in an extra system, solving both problems at once. So, try removing your existing page breaks but then adding system breaks on measures 17 and 45, then a new page break on 51. Much better results (see attached).
For the record, if you are trying to match an existing non-optimal layout that does have only three systems on the last page for whatever reason - or ever find yourself in a situation where this is for some reason unavoidable - it's usually better to allow the extra space to be distributed throughout the page as MuseScore does by default. But sometimes - depending on the specifics of the score - it can be a bit overly aggressive about this, as would be the case here if you removed the extra frames and spacers and did nothing else, so tweaking
In this case, I'd probably reduce the factor for distance above/below brace to 1.0, and reduce the page fill distance to 1. Then the extra page isn't fill out quite so much, and the lyric staff doesn't "hog" the space.
Another option if you want to include room for people to write in notes at the bottom of the last page would be go to ahead and bunch the space all up at the bottom. That's accomplished very simply by just putting a spacer below the last system.