Dear experts,
I have electronically signed my macros to enable my coworkers to simply
check the checkbox "Always trust macros from this source" in the macro
security alert, and not be bothered with it anymore.
It works on my computer, but in some other computers the checkbox line is
grey and you can't check it. The security level for macros is medium on every
computer.

What could the reason for this be? Can you please help me?
Many thanks!
Valeria