I have G E side by side fridge that is one year old. It has suddenly stopped being cold enough to freeze and fridge doesnt seem cold enough. It has a setting on the outside that you can change the temp but once you try to reset it, it just changes back to whatever it wants to

Change to a lower temperature and save the settings ..by pressing save ..or whatever it sais...if you just made the change but not confirm the saving of the new setting it is normal to get back to the old value..
Im dont know the exact model name to guide you ..but if you still have the manual it is explained there ..if you do not have it ..let me know the exact model and I will prvide a manual if I find one...but in short . assuming that the control panel is working well you insert the new value on the change temperature feature..and save it ..to be sure you have what you wish ..
resetting it it gets to the factory default ..and Im not sure it is what you need..