The "revert" stack order gets read in whenever you read in a portfolio file. (That happens at program startup automatically usually because of the "Options / General Preferences... / Data / Open Last Portfolio at Startup" option, which is on by default.) It doesn't update the "revert stack" when you save your portfolio. This really wasn't intentional either way, but that is how it works. I updated the verbiage in the documentation on the investment stack to clarify this point.
The Revert Order command puts the investment stack back to how it was read in from the currently open portfolio file.