I have created a macro-based Excel spreadsheet for a client.
Currently the client has to change their security settings to medium
or low in order to use the file, but they find this cumbersome and
would like to not have to do this. Especially since this file will be
used by many different organizations, and we want to make it as easy
as possible.

I believe the answer is to get a digital signature for the workbook,
but after a little research and googling around, I'm still unsure how
this process works. Is it possible to get something (they will pay
for it) so that no matter what the security settings are, the workbook
will open and work correctly for everyone?

If anyone has experience with this, I'd greatly appreciate some
insight.