Saving edited texture mac

[Artsteams]

Hello,

I have a mac and edited an existing texture (changed color, hight and width of the bricks,...). Now I would like to save the changes I made to create a new texture and use it in a different model, but I cannot figure out how to do it. When I want to upload a New Texture in the Color panel I need a saved file and when I try Edit Texture Image to save the new one, the image I get is the same as the original.
Could someone please help me out?
Thanks!!

Evelien