There is no way to edit the source and destination of an existing pair other than deleting it and creating a new pair.
Unfortunately, SyncToy v2.1 has some serious problems. It's easy to synchronize SyncToy execution using the Windows Task Scheduler. One can complete the synchronization at that point or cancel it. The option "Preview All" runs SyncToy as far as determining which files would be changed on execution.
"Toggle All Checks" which converts each checkbox to its opposite.
"Uncheck All" to turn all of the pairs off.
Right-clicking anywhere in the window brings up three useful options: The "All Folders Pairs" display lets the user select whatever pairs are suitable for a specific synchronization those pairs marked as "Active for run all" are automatically checked.
"Check file contents" is explained in its Help pop-up as, "specify to examine file contents in addition to name, size and date to determine if two files are identical.".
Deleted files can be saved in the Windows Recycle Bin.
Clicking "Run" in that display activates all the selected synchronizations.
"Active for run all" means that a particular synchronization pair is automatically selected in the overall "Run all" display.
File menu for selecting subfolders this feature provides complete control over exactly which subfolders are to be synchronized in any parent folder.
Checkboxes for "Exclude read-only files," "Exclude hidden files," and "Exclude system files.".
Wildcard characters for inclusion and exclusion filters.
Renames on the left are repeated on the right.
Contribute: "New and updated files are copied left to right.
Renames and delete on the left are repeated on the right." Here, left means the source and right means the destination.
Echo: "New and updated files are copied left to right.
Renames and delete from either side are repeated on the other."
Synchronize: "New and updated files are copied both ways.
One can create a new folder pair, delete an old folder pair, and rename any folder pair from this window. SyncToy Version 2.1 is available for 32-bit and 64-bit Windows. The product allows us to define synchronization pairs: folders or even entire volumes that we want to ensure are identical on source and target.