using computer A on surface B - what best tools to do that?

using mouse keyboard display of surface B to use computer Awhat best apps tools to do that?​tried using projecting pc but had lots of porblmesand nobdy know why > https://www.reddit.com/r/Windows10TechSupport/comments/kkx38b/projecting_to_this_pc/​alos how use ios phone on windows 10and how use android tablet on windows 10?