Have a kitchenaid microwave KHMS2040WSS brand new. Is there a way to set the popcorn sensor for a smaller bag? Right now it is set for 3.5oz and burns all the popcorn.

The microwave burnt it. It will be a bit of trial and error with using your new microwave and will also depend (in this case) the brand of pop corn you've cooking. Check the recommendations on the pop corn packaging for time and heat range. Happy popping!

Most M/W use an estimated setting based on ounces of corn. I've found that many do not tell you how much is in each bag. The bags usually have no size markings. Check the face of the box for something like "2 each 3 oz bags".
* Try to use a normal re-heat setting (at full power) and cook a bag using the a minute longer than the recommended setting. Listen to the popping sounds and stop the M/W when the pops slow to 3-4 seconds. (2-3 seconds with 'Kettle' corn) Note the time lapsed and this is your correct setting. You may try the popcorn menu to find a similar setting but really your best bet is to use the method above as it's the most accurate.
* Note; Old or stale corn will not all pop (it dries out as it gets older and there is not enough moisture in the kernnal to steam pop.)
* M/W varies from model to model and brand to brand. Only way to check is to try several settings to get the best results.
* Pop corn brands vary in quality. You will find the better name brands pop more.
* Once you find a good popping brand then stick to that size and brand. (unless they change it on you.)
* If your really stuck on getting every corn kern popped then go with an air popper. It won't come out of cooker till it pops.

Good movie, don't forget the goobers, milk duds, frosty...
Aloha, ukeboy57

I would be in the market for a new oven right away.

If the microwave functions normally while cooking everything else, but is only burning popcorn, there is no component problem that will cause this. You cannot adjust or replace any internal component to make it not burn popcorn. All power levels and program options are contolled by the consumer at the control panel. Refer to your owner;s manual for their recommendations.

If the oven is equipped with a popcorn feature button, it is programmed for a recommended power level and time. This is an ESTIMATED program feature. The manufacturers of both the oven and the popcorn will also give directions that tell you to turn the oven off when the popping slows to about a pop every 2 seconds. Failure to do so can result in burning.

If the microwave does not come with a popcorn feature button, the manufacturers of the popcorn have directions on the outside of the box that tell you what POWER LEVEL and TIME to set the oven on for the desired result. Again, the you still have to listen as the bag pops to ensure it does not burn.

In addition, on some microwave ovens, there is a feature that allows you to select the SIZE of the popcorn bag. Some popcorn manufacturers have smaller snack size bags that don't take as long to pop. You have to select the appropriate size to get the correct program option.

In any case, you never are to place popcorn in a microwave oven and walk away from it. All these program features are ESTIMATIONS based on manufacturers testing and recommendations for the best results. All microwave ovens are different and operate at different power levels. Your best judge is to listen as it pops.

I hope this helps you.

Generic questions and comments:

Does your microwave have a "popcorn" setting and are you using it? Is there a rotating table in your machine? Is your popcorn bag elevated on top of a bowl or similar? Are you using some other "sensor" setting? Can you use straight time setting and get it to go past the 1 min 45 second mark?

On my microwave, it takes just about that much time and the popcorn is done ... BUT only if I elevate the bag to about the middle of the oven.

Let me know if this works for you.

a

try a different brand of popcorn & let me no what happens

Awesome.

We had the same problem with our brand new Magic Chef. Before going through the trouble of taking it back I called Home Depot. After talking to a Home Depot Rep I am told that the overheat sensor is under the glass plate directly beneath the popcorn bag. Popcorn gets very hot and the heat of the popcorn causes the sensor to shut the machine down. I would imagine this would be the same for a baked potato.
Very poor design.
I was told to put a microwave safe plate down and put the popcorn bag on it. This should help to reduce the heat and not trip the sensor.
A safety sensor is great, but not if it keeps tripping the machine and shutting down!