I asked myself the same question, thanks for the answer.
The description "manual mode" and "automatic" on the dialog page seems unfortunate, because you expect that you somewhat switch/change some general behavior of the application, especially if you switch from automatic to manual or vice versa. But in fact you don't change anything.
In fact, you only change the default location of newly created items. Not even existing items. You only change the default location of newly created bookmarks/identities/etc.: "automatic" means "default location for new bookmarks/identities/etc. is on myTeamspeak" and "manual" means "default location for new bookmarks/identities/etc." is local computer. If you don't ever create any new items after switching this setting, this setting is meaningless. Instead, you expect that you change the sync setting of all your existing items.
This could be made more clear in the description of the sync option. Perhaps like this:
Code:
[x] Synchronisierung
Speichere neu erstellte Identitäten, Favoriten, Whisper Listen, Hotkey Profile:
(*) auf MyTeamspeak (können nachträglich nach lokal verschoben werden)
( ) lokal (können nachträglich nach myTeamspeak verschoben werden)