@nata4444
1. This was the Access365 ribbon options screenshot I mentioned before:

2. No Access database can ever be completely secure from a determined and skilled hacker with time on their hands.
The article I mentioned is outlining ways of
improving security and is sufficient for almost all circumstances.
Agree totally that if you know how, almost any security can be bypassed.
In general, if your data is that sensitive, it shouldn't be stored in Access.
However the encrypted split no strings approach is about as secure as any Access app can ever be.
You can easily test it for yourself by trying to crack the example app provided.
So far, nobody has mentioned to crack it using VBA
3. Section 5 c) of that article explains what causes the QAT to be locked. I've even highlighted it in RED