Whenever you are going to work on a preset, if you initially duplicate it onto your available A or B window, you will always have its initial settings that were copied, available within the adjacent window for comparisons, as you make changes on your alternate.

Once a preset appears with the word modified italicized, it seems difficult to save accidentally, since your now saving it necessitates a prompt window and your acknowledging it via a cursory click to either accept or cancel.

If you ever do save changes to any preset, unintentionally, undos restore your previous settings.

Hi.  Thanks for the response.  O just noted that when I made a change the preset name appended (modified) to the name.  That worries me, since I don't want to mess up the originals.

The "modified" is just a reminder you might want to save the modifications into a custom preset, nothing to worry about. If you change presets the modifications are discarded.