Some actions cannot be undone: for example, applying the Collapse utility or Reset Transform utility, or saving a file, which overwrites the previous version. When you know an action cannot be undone, use Hold first. Then if you want to undo it, use Fetch. Hold and Fetch are also commands on the Edit menu.
Afer you perform an action that is undoable, the Undo command on the Edit menu shows the name of the function to be undone. After you undo an action, the Redo command Edit menu shows the name of the function you can redo.
Undo and Redo are also available as buttons on the main toolbar. On the main toolbar, right-click the Undo or Redo button to see the list of recent operations. You can highlight and reverse any number of these operations in sequence with the respective Undo or Redo command. By default, there are 20 levels of Undo. You can change the number of levels with the Customize Preferences General tab Scene Undo group.
When you create an object, the Create operation is recorded by 3ds Max and displayed next to the activated Undo command in the Edit menu. If you undo the Create operation, the Create operation appears next to the activated Redo command in the Edit menu. The Undo and Redo commands in the Edit menu are unavailable when no valid operation was performed or recorded.
To undo the most recent action:
Do one of the following:
To undo several actions:
To exit the list without performing an action, click the Cancel button, or click somewhere outside of the list.
To redo an action, do one of the following:
To redo several actions:
Your selection must be contiguous: you can't skip over any items in the list.
To exit the list without performing an action, click the Cancel button or click somewhere outside of the list.