I found herehttps://www.sdn.sap.com/irj/sdn/thread?threadID=211383">here> a suggestion on how to prompt selection variables in a Web Template when users are switching from one query to another via New Analysis button.
I actually added as new command in the "New Analysis" button the SET_VARIABLES_STATE command with parameter Display Variables Screen=On. Sequence is Load first and this command second. Unfotunately when i run a test the variable window is opening first with a blank window .
We are on SP12 and it's mentioned this solution should work from 9 on.
I'd really appreciate an help from you guys.