I have been playing with this for months. Our company tightened up
security policies, and now, whatever I select the macro  security level
to be, it defaults to High at next Excel start. So I wanted to
programmatically change  it.

But, no joy anywhere on the web. I had to resort to digitally signing
all my workbooks' code, but now it all works again.

You may also find on other groups that people are hesitant to answer
your particular question, as the technique can be used by hackers to run
malicious code on someone's computer.

If your specific query is about someone else's computer executing your
code, there is no alternative but to have them accept your security
certificate as valid, or alternatively Enable Macros on every open of
the workbook.

As much as I rebelled against the extra steps, I know why the company
needs the protection, and thus in the end I conformed!