I'm not sure what you mean, there's no default Office
suite as far as I know on my 2 Win 10 systems.
Do you want to change the default for (for example) .doc(x) files to LibreOffice, in which case Settings/ System, Apps/ Default Apps is the way to go.
from the Windows 10 Forums may be of help - it shows the large variety of ways that default apps can be set up in Win 10.
Edited for clarity & typo
We have more and more laws, and less and less enforcement
Edited by cheshire_man (Fri 04-Mar-16 07:23:11)