cmogletree-
If you are using the standard address fields found an a Work Order(Activity table), they are linked fields and cannot be updated through the work order. The value for these fields will always come from the Entity (The customer you selected).
If you go to Customize > Tables / Fields and click Edit fields... for the Activity table, you will see that the fields you are trying to use have a value in th Linked Via column.
To get this to work properly you will have to add new fields for the address.
-Michael