software

My problem is that I want to change the source workbook but the Change source button is not available? The source file updates weekly (one for Monday, tuesday, etc). Before these files are updated, they are archived to a different folder but all under the same name (i.e. MON TUE WED etc.). I want my formulas to compute using the archived files but the Change Source button is not available! I had to change the formula references in each of the 30 workbooks containing 9 wokrsheet each!!! HEEELLPPP!!!

oh... and even the UPDATe NOW button is also grayed over.... i've tried playing around with the setting in the Calculations tab of the Options menu but I can't seem to get it... should the settings be changed to manual?... which buttons should be checked/unchecked?