It is unlikely that you need to change all your cartridges at exactly the same time. On occasion this happens, but it is not a requirement that all cartridges are changed. You should be able to tell which cartridges need changing from either the printer or the software on your laptop / PC. Determine which cartridge needs changing and only change that particular one. The only time you may wish to consider changing all cartridges together is if you are planning to do a big print run or some special photographs, in which case you would not want to run out part way through.