Folder HelpDesk Changes not saved

My changes are not saved when I edit a ticket.

lease look if the ‘Save email history in ticket body’ is 
enabled under the tab Other Settings in the Folder HelpDesk Settings. 

If you use that alternative for e-mail threading, the tickets cannot be edited freely. You can only append text above the existing body. If you put anything in between, it won’t be saved. 

If you think this is the problem, you can either uncheck ‘Save email history in ticket body’ 
or restrict yourself to only add text above the earlier text.