How are uniform tga's altered correctly?

[Tomas23]

i know this might sound stupid, but when I want to change something on the uniforms, or whatever, I copy the .tga file to another folder (create a new one somewhere). I open it with Irfanview 4.23 and save it as a .bmp file. I open the .bmp file in 'paint', make my changes, and save. I reopen with Irfanview and save it as a .tga file. Copy and paste back into original folder.