Dues Query

I have a employee database. In the database, union members are a subset of
employees, as such their "member status" is "member" or "member-LOA" while
non union members are identified as "non-member" or "retired". Periodically
the membership dues change for all members; non-members are not affected.
When dues change all members need to have the field updated. I do not want to
get involved when the dues change so I want to create a query so the database
manager answers a prompt (new dues amount) when they select an action button
from the menu (Update Dues). There are no issues with archiving the previous
field data so just a mass update. How can I set this up?

Thanks