Well some sort of detailed information might help.
What sort of threat, e.g. what was the malware name given in the avast detection ?
What version of photoshop ?
May be that this is an old unsigned version, which falls foul of the AutoSandbox ‘file prevalence/reputation is low.’ I have had that with very old versions of MS Word and Excel, I just added them to the AutoSandbox exclusions.
What action was taken on the detection, the default action is to send it to the chest ?
From here it is possible to Restore it from the chest (after confirming that the detection is false), when you set an exclusion for it.
Confirm or deny the detection - Report to avast as an FP if only avast detects at virustotal. This gets avast to modify the signature so it isn’t detected, this helps all users who may have the same photoshop.exe version.