The screen says you cannot do something. That is a role you have not been given. Ask your manager.

A button does nothing. Check whether the page is still loading. If it happens again, note which button on which screen and tell your manager — that detail is what lets Humint find it quickly.

You cannot find a patient. Type at least two letters and give it a moment. If they are genuinely not there, create them.

You lost what you typed. Everything on the examination screen is saved by the Save button at the bottom. The only buttons that leave the page — Fitting and Preview Quote — save first, so the usual cause is a browser back button. Type it in again and press Save.

Something looks wrong on an invoice. Do not delete it. A draft can be corrected; a posted invoice should be reset to draft or credited, so the trail is kept.