Maybe other windows or mac backup apps do this automatically/silently when you select drives by their drive-letter or via some file-select dialog box, but I don’t think SyncBack does (from experience!)
Luckily, you can set backups using Serial Numbers like this
For example, if your external drive has a serial number of ABCD-EFGH then you could set your source or destination to:
%SERIAL=ABCD-EFGH%\backup\
(This is maybe only of some importance to people with external drives…?)
