To undo or revert to the previous Style - type S4 or Shift+F9 in any bar of the Chord Sheet and press Enter
The current style will be listed at the top and the Style beneath the first Style is the prior style the current style replaced.
Up to 150 previously used styles will be listed
There are other useful options with this method

Attached Files (Click to download or enlarge) (Only available when you are logged in)
Style Open Selections.jpg (48.72 KB, 25 downloads)

BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.