How do I know if the malware is gone?

Ok, so recently I came across malware that was on my computer. I noticed this as my Microsoft-account was heavily edited so I no longer had access. Now my steam pfp keeps getting changed and my account has spammed the friendslist with explicit photos. I ran a fullscan of the pc and it detected a corrupt file named "trojan" with a bunch of symbols and numbers. Naturally I deleted it on the spot and ran a full search again, but this time the pc found nothing so I thought it was gone, but my steam account is still changing the pfp and sending messeges so idk what to do about it, and frankly I'm afraid to reset the whole pc.

so please, if anyone can help :')