How can I switch my rival programmable crockpot to warm? It was cooking too long and I'd like to switch it

yes you may as long as you do not over fill it you are fine to cook less than six qrt.

Add more liquid. If it is still getting too hot, check to see if it has a temperature knob on it somewhere, if not, you can release some of the heat by removing the lid slightly to let steam and heat release from it as it cooks

I couldn't find the specific manual for this, but I did find some basic instructions on a personal review:
"Rival calls this a SmartPot and describes this unit as "programmable". All this really means is that you can program the slow cooker to cook either on "High" or "Low" for up to 20 hours, in 30 minute increments and then it will automatically switch to the "Keep Warm" setting and keep your meal warm for hours. You cannot program multiple steps, such as going from the "High" to the "Low" setting. The red, LCD clearly displays the remaining cook time.
Simply plug in the slow cooker, and then push the clearly marked buttons (with a pleasant, audible tone) to move from "Low" to "High" to "Keep warm" settings. Then push the Timer Button to set the desired cook time."
Hopefully, this helps answer your questions!

Your crockpot heat unit is overheating. Return it to the store you purchased it at or contact the manufacturer. My Rival did that and I contacted the company and they sent me a new one.

no 0=off........1=low.........11=med..........pot=high,cook ......

If you still have your base for the Rival 3355 Crockpot and aren't using it. I would LOVE to buy the handles from you. Mine are cracked but the other parts work fine. [email protected]

The handle on my rival 20 quart programmable roaster oven is broken. Where can I get a new handle?

I have a stoneware round, forest green liner for a Rival crockpot. I think it's for a 6 quart because I only buy the larger crockpots for my cooking needs. If you would like this, please email me at [email protected] so we can exchange addresses.

hhh

Here is the manual for this cooker; http://www.crockpot.com/manuals/38601-C_English.pdf page E4 and E5 tells you details of programming/timer/temperature. Check through everything and see if you can figure anything out. after cooking, the unit should automatically switch to warm mode, if it isn't doing this then unfortunately i think it needs a replacement control board - probably not worth doing. If you want to give it a try then post again and we can try and source you the bits Hope this helps :)