Assurance they aren't trojans is worthless, conformation is priceless, so you should first confirm using virustotal as suggested, rather than hope someone else reports it and avast corrects it.
The only way to resolve it is to confirm they are FPs and to submit samples for analysis.
If the files aren't too large:
Send the sample to virus@avast.com zipped and password protected with the password in email body, a link to this topic might help and false positive in the subject.
Or you can also add the file to the User Files (File, Add) section of the avast chest (if it isn't already in the chest) where it can do no harm and send it from there. A copy of the file/s will remain in the original location, so you will need to take further action and can remove/rename that.
Send it from the User Files section of the chest (select the file, right click, email to Alwil Software). It will be uploaded (not actually emailed) to avast when the next avast auto (or manual) update is done.