Crystal-Financial Statements-Selecting the month

So I have a Crystal Report built where I am showing financial data Primarily from the GLAMOUNTS and FBDETAIL tables. The report basically looks like this:
Company | Account | MTD Actual | MTD Budget

Its subtotaled at the company group level.

So for one month its working correctly.What I want to do is make it so that the end user is picking the month they want to see from a drop down list rather than creating a report per month or a report that lists all months.

The problem I'm having is that GLAMOUNTS and FBDETAILhave one field for each month (Actually 2, one for debits and one for credits which I have combined in the command to be one field). Parameter field options seem to only want to work with the data inside one specific field.

* What do I need to do to allow the user to select one month?
* Is it posible to have the user select one month and it gets the correct field for both the actual and budget or do they have to select twice, once for budget and once for actual?

Thanks

Dave