You need to be logged on as Administrator or using an account with administrative priveledges in order to be able to reset the archive bit in Windows.
If it is not possible to use administrator account, you can switch off the "reset archive bit" setting, from the Job Settings tab. The archive bit is a "flag" that every file has and can be used in advanced backup types, to backup only the files that have changed since the last total or incremental backup. If you are always performing a backup of type "Total Backup" (also from the Job Settings tab), you do not need the archive bit information. A backup of type "Total Backup" means that all selected files are backed up, irrelevantly if they changed or not since last backup.
