I want the technicians to be able to add their own problem and status value instead of limiting it from a few pre-defined values in Outlook and SharePoint. How can I achieve it?

By default, in the new ticket form, individual technician can only select a value from amongst the administrator predefined drop down lists for the problem category, type and status fields.

To change this behaviour and to allow technician to key in their own value in these drop down fields, enable the option ‘Allow Technician to add their own problem category and Type Value’ under Issue Tracker ribbon/toolbar >Team Settings > Advanced Team Options. Note that this changes in this option will only take effect in the Outlook of all technicians once they sync the settings, or Outlook has been restarted (and assuming that the auto-sync at start-up is enabled).

Now, individual technician would be able to add their own problem and status value instead of limiting it from a few pre-defined values in Outlook and SharePoint. This option also takes effect in SharePoint list Form.