This is easy just press the tab that says font (second row down) or sometimes it's at the top of the screen.
You can't, sorry.
Well, if you're changing small font to capital font in Microsoft word, use the CAPS LOCK key. Though, if you're talking about too many text, I'll suggest to highlight the whole text and right click...
For PC : Control Panel\Appearance and Personalization\Personalization ,click on theme and make font changes to elements that use fonts.
go to control pannal and then go to users and edit only on a new computer tho.