if you used your own fabric hopefully you prepared it for dyeing- by prewashing-with detergent- dried-no fabric softener-
and used good (permenent) ink in your printer- the re=fills & generic cartridges are water soluble-and wash out
after allowing the ink to cure (soak into the fibers & dry) heat set with your iron on cotton- place a (pressing cloth) over the picture (like a square of muslin)
if you used pre-packaged fabric printer sheets- you need to follow the instructions on the package- each different brand has their own requirements/instructions-
when i make my own i usually set them aside for 24 hours (to cure) then heat set- after cooling take to sink and run cold water through- some excess ink may rinse out but the picture should stay 'sharp & clear'
HP & Epson printers offer the best choices in inks that are permenent and work well for this.