To do Alt + M X A on Mac in Excel, download and install Accelerator Keys, then press Option, followed by M, X, A.
Command: Automatic Calculation
This is how to do Alt + M X A on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + M X A sets Excel’s calculation mode to Automatic. In this mode, Excel recalculates all formulas whenever you change a value, insert or delete rows/columns, or rename worksheets. This is the default setting and ensures your data is always up to date.