1. Regarding your first issue - did you perhaps disable third-level categories? There is a bug in the mobile app regarding this situation which was fixed and will be implemented in the next version soon.
2. Regarding being unable to login - this will require further investigation with support. Please provide device model, app version, and logs (side menu > Settings > Send Logs).
3. Regarding sharing of data - can you please clarify? How would you see this implemented?
4. Regarding being unable to change status - can you please clarify? If the Categories are a required field, then it shouldn't let you save the ticket until filled by design. Unless I'm misunderstanding.