Syncthing stores all configuration in a single folder. The location of the folder is OS-specific and documented here.
Be aware that this folder also contains syncthing’s internal database. Restoring the database from a backup can potentially be dangerous. It’s fine to backup the database, but the database is capable of rebuilding itself and so it’s possibly safer to not restore it.
(Also note that SyncTrayzor has another custom directory where SyncTrayzor specific settings are stored. The SyncTrayzor config-folder can be found @ %AppData%\SyncTrayzor)