How do I expand all columns in Excel spreadsheet?
Click where the row and column headers meet, this will select the entire sheet, like so:
Then double-click any one of the column partition lines.
I do this all the time, and it's as quick as you can get.
I don't know about shortcut. I use menu.
1) Select The Full Spreadsheet
2) Select Format
3) Column
4) Autofit Selection
Ctrl+A to select all cells, then press Alt+H, O, I.