Model #PSC25MSTA SS - one year old, never got a manual with refrigerator, don't know how to lower the temperature. suddenly, ice cream melting; milk sour; push buttons to lower temperatures, does not set a lower temp. how do I set a lower temperature. Frig tem is 42; freezer says -1, yet the ice cream melts.

At -2?F ice cream should be solid. Try this, store the ice cream on a lower shelf.
If that does not work, get a freezer thermometer and check the interior temperature.

You need to change the settings on the thermostat. Its a dial setting inside or digital setting on the door. Lower the temperature until you are satisfied.

What make and model is "this" ice cream maker?

I had one of these many years ago and, whilst I cannot remember the proportions, you warm the milk and the butter (unsalted!) very gently until the butter just melts (or melt the butter separately and add to the milk). Then put it through the machine. I seem to remember you often had to make two or three passes to get all the butter and milk to combine.
I guess that the proportions of milk to butter are quite flexible depending on what sort of cream you want. I'd try small quantities till you get the required result. Start with one part butter to 2 to 4 parts milk by weight.

Sounds like you might have a leak in the sealed system and it is gradualy getting worse.

If you do not have guages (freon) and have a licens to proforme this type of work you will need to have someone qualified in this area to varify.You can call sears home repair @ 800 469-4663

You use ICE, not water and then rock salt is added over the ice to lower the temperature for making the ice cream.

The salt hastens the melting of the ice and thus lowers the temperature.

I can't give you a solution but I can tell you that we have exactly the same situation. The freezer seems to work but we come back and water has dripped from the ice holder and formed a classic stalagtite (or is it a stalagmite?) Obviously something has melted. We have also found items in the freezer melted - yet the digital readout said it was 3 degrees! Arghhhhh. Glenn in Delaware

Rock salt is also used to make ice cream. It is not actually used in the ice cream mixture; rather, it is used to melt the ice surrounding the can holding the ice cream, causing the ice to melt at a lower temperature, thus lowering the temperature of the ice bath and quickening the freezing process.

i tell people to judge the fridge and freezer by using your milk and ice cream everyone knowes how they like their milk and it is usually the first indicator of cooling problems and you want your ice cream firm but not so hard that you have to dig it out with a jack hammer and Etheline is a consideration