Make My Adjustments Un-Doable Forever?

Instead of applying an adjustment directly to your image (by going under the Image menu, under Adjustments, and choosing the adjustments there, like Curves, or Color Lookup, or Hue/Saturation, etc.), choose any one of these adjustments from the Create New Adjustment Layer icon’s pop-up menu at the bottom of the Layers panel (it’s the fourth icon from the left, and it looks like a circle that’s half white/half black). This adds the adjustment as its own separate layer above your current image layer, which you can re-adjust at any time (just click on that adjustment layer and the controls reappear in the Properties panel) or delete permanently by dragging that adjustment layer onto the Trash icon at the bottom of the Layers panel. Here’s why this is such a huge advantage: Normally, when you work in Photoshop, you get 20 undos. After that, it won’t undo any more steps. However, by applying these image adjustments as adjustment layers (rather than choosing them from the Image menu, under Adjustments), and saving this file as a layered Photoshop file with all those layers intact, you could reopen this layered file and edit or delete an adjustment next week, next year, or even 10 years from now. So, it’s like an undo that lives forever. Of course, if you flatten the file, all your layers go away. So, to retain this “edit forever” capability, remember to save a version of your image with all those layers intact (save it in Photoshop [PSD] format—that keeps your layers intact—rather than saving it as a JPEG, which flattens your image).