Photo prints will yellow if improperly washed. We wash prints after the fix bath to completely remove residual chemicals. Try to save these prints by re-fixing and then washing in running water for about 15 to 30 minutes in gently running water. If water is scarce, use a washing agent like "hypo clear" followed by a brief wash. If this doesn't work, let us know, their are other remedies but these are more complex.
The more complex – don’t attempt if you have not taken chemical handling safety 101. We gray-hairs worked in the dark with loads of chemicals. After all film and paper developing is a subset of the chemical industry.
To remove stains from prints improperly washed:
Prepare a stain removing bath:
Potassium Alum (saturated solution) 250 milliliters
Hydrochloric Acid (concentrated) 6 milliliters
Pour the potassium alum into a tray sufficient in size to accept the prints.
Pour slowly into this tray the acid while stirring constantly.
Soak the stained prints in this solution, all carried out in normal room light.
Wash the prints in running water thoroughly after treatment.