I have a simple image with an off-white background. I would like to make that off-white background be pure white. I can use the "Replace Color" tool to select the off-white but I don't know how to then get that selected color to be set to my desired color of pure white.
I can recommend the use of the magic wand tool¹ to select only the white you wish to recolour using the tolerance meter. Afterwards it is a simple matter of using the paint bucket tool set to the desired color of pure white.