As mentioned in comments, the update statement will only update 1 table at a time. Hence
Update table SET field = value
You will need to do 2 different update statements.
One option is to store in a temp table all the ids of the fields that you need to touch so that you can do 2 updates and make sure you get all of the relevant fields. However, depending on your logic, a temp table may not be required.
Also, you should likely do this in a transaction so that if one update fails, both are rolled back.