Ever down loaded a .gif or .jpg file and had trouble editing it. Tried clicking on the pad lock icon in the layer panel,but it want unlock.
Don’t worry this is a very simple fix. Just go to the image menu tab at the top of photoshop and then mode, you will see that the “indexed color” mode is ticked, now just change this to rgb color or cmyk color. Then go to the padlock again and try to unlock it now, you will find it works fine now.
Hope that was helpful.