Quick Questions - Change Passwords After Threat Detected?

[REDACTED]

Hello,

 I have a quick question - usually when a threat is detected by a scan I will panic a little bit and change all my passwords. I was just wondering whether this is necessary? Only because I recently found out that Avast scans files as they are moved, opened and used within the system (so even remembering to scan regularly isn't as important). Am I therefore correct in assuming that any threat detected within a manual scan is a virus/malware that hasn't actually done anything yet? (since if it had, the file shields would have flagged it earlier). And therefore, that this means that anything found by Avast won't have done anything to my system? In which case, there isn't really anything to worry about anymore and I'm good not to panic/change all my passwords?

 Sorry if this is a silly question!

 Thanks

[Eddy]

Changing passwords on a regular base is a good thing to do anyways.
If it is needed to change them when a thread is detected depends on the threat.
Threats don't just come with files, there are many others.

[Pondus]

Only because I recently found out that Avast scans files as they are moved, opened and used within the system (so even remembering to scan regularly isn't as important).

All AV programs does this ... Except one