1. Create a macro named "AutoKeys". (The name is important).

2. Show the Macro Names column View menu.)

3. In the macro column type a caret (Shift+6) followed by an S.
In the Action column, choose an innocuous action, such as Beep.

4. On the next line of the macro, specify the next key combination.
Your macro will now look like this:
   ^S            Beep
   ^F            Beep

Now Ctrl+S will be handled by the macro instead of the default.

You can reassign Ctrl+F4 with the name:
   ^{F4}
In general, you use the percent charater (%) to represent the Alt key
combinations, but %{F4} is not permitted. To disable Alt+F4, you would need
to use the KeyDown event of each form.

The question arises as to why you are doing this, as it is likely to
frustrate good data entry operators, who invariably know the standard
shortcut keys and find it faster than the mouse. Is is just because you
don't understand how to design an event-driven program? For example, if you
want to run some checks before the record is saved, the BeforeUpdate event
of the *form* will let you do that.