How do you sort columns left to right in MS Excel for mac?
To rearrange columns alphanumerically by their names, assuming the column names are in row 1, do this:


Select all cells of the table. (Click and drag from top left cell to bottom right cell.) 
Click the thin arrow button next to the 'Sort' button and choose Custom sort…. 
In the Sort dialog box, click Options…, and in the pop-up, choose to Sort Columns.
Back in the main dialog box, un-check 'My list has headers'.
in Row: select Row 1; in Sort On: select Values; and in Order: select A–Z.
Click OK to execute. 


(based on Excel 2011)