When you save a file you’ll quickly see places available for the account you're signed in to. This way, the Office files you store in online locations like OneDrive and SharePoint are always at your fingertips wherever you go.
If you're used to using the Save As dialog box from earlier versions of Office, you can go back to using that: Click File > Options > Save, and then check the Don’t show the Backstage when opening or saving files box. The setting applies to all your Office programs.
If you want to use the Save As dialog box without making a setting across Office programs, just press F12 instead of Ctrl+S when you save files.
Change how many recent folders you see by clicking File > Options > Advanced. Under Display set the number you want to see in the Show this number of unpinned Recent Folders box. If there's a folder you always want to be shown in the list, hover your mouse over it in the list, and then click Pin this item to the list.
If you want open a file from or save a file to your Windows (C:) drive, you first must run your Office app as an administrator.