I put in a new set of 4 cartridges in February. Since then I've printed about 500 pages in monochrome black. I have my printer set to greyscale and don't think I've printed more than one or two pages in color yet my Yellow cartridge is down to about 1/3 left, the Cyan cartridge is down to about 3/4 left and the Magenta cartridge shows full.
Can anybody explain what's happening.