How to Auto-Select Previous Month by Default in a Month Selection Dashboard?

Hello Everyone,

I need your help with a requirement.

My requirement is to have a button-style Month Selection on the dashboard where users can select a month and view the corresponding data. However, when the workbook is opened, it should automatically select the previous month of the current month by default.

For example:

• In August 2026, the default selected month should be July 2026.
• In September 2026, it should automatically select August 2026.
• When moving to the next quarter, such as October 2026, it should automatically select September 2026.

The month selection should always display only the current quarter months and previous quarter months.

To meet this requirement, I have created this sheet and a Time Shift Parameter, where:

• M1, M2, M3 represent the current quarter months.
• M-1, M-2, M-3 represent the previous quarter months.

Could you please review this approach and suggest how I can make the month selection automatically default to the previous month while still limiting the available selections to the current and previous quarter months?