If you have applied effects to a photo, then try some other action that requires adding other effects - the app prompts "photo already has effects. Please reset this before applying these effects." (or something like that). Cant the pop-up dialog offer a "Replace old effects with new" - to save having to find the reset (buried in a sub-menu!) or the keyboard short-cut and the repeat the action you wanted?
And to help all this.. Please could objects that have effects be marked with an 'fx' symbol - and if you hover over the symbol it could summarise what the effect is?