I dont know how to use the oven properly. when i need to bake or roast something i want to put in my own temperature, but there is no option for me to do that. when i turn on the stove all i have is the options bake roast ect. and the temperature starts at 120 to preheat, then it gets to 200 range not higher. the question is how can i put in my own temperature instead of using the functions that the stove already have?

A Model # would help us allot

If your built-in electric oven is getting to temperature and then quitting during a bake cycle, and the upper heating element is not working during the bake cycle but works on the broil setting, it is possible that the problem is with the bake element. Here are some troubleshooting steps you can take:

1. Check the bake element: The bake element is the heating element located at the bottom of the oven. To check if the bake element is working properly, turn on the oven and set it to bake mode. Open the oven door and look at the bake element. It should be glowing red. If it is not, then the bake element is likely faulty and needs to be replaced.
2. Check the oven temperature sensor: The oven temperature sensor is a small probe that is located inside the oven. Its job is to monitor the temperature inside the oven and communicate that information to the oven's control board. If the sensor is faulty, it may cause the oven to shut off prematurely. You can test the sensor with a multimeter to see if it is working properly. If it is not, then it needs to be replaced.
3. Check the oven control board: If both the bake element and the oven temperature sensor are working properly, then the problem may be with the oven's control board. The control board is responsible for controlling the oven's heating elements and other functions. If it is faulty, it may be shutting off the oven prematurely. In this case, the control board will need to be replaced.

It is recommended to hire a qualified technician to perform these tests and replace any faulty parts to avoid any risks of electrical shock or damage to the oven.

you can recalibrate it yes.

https://forum.appliancepartspros.com/posts/t191937-thermador-oven-temperature-thermostat

It's on page 32 of the manual for Thermador's built in convection ovens.
1. turn off the oven
2.touch and hold the start pad and then touch the bake pad
3. 0 (zero) appears in the temp digits. release all pads
4. touch bake and 0 changes in increments. max adjustment is 35 degrees F.
5. to complete change touch start for lower oven on double ovens do this: touch the roast pad instead of the bake pad continue with steps 3-5.

Please always include full 'make model (what it is)' in all questions.

is this 400c or 400f

ensure that your convection fan is turning
a hum on this model usualy means that the convection motor can seize up a bit
sometimes all you need to do is redjust the fan blade

You could contact the manufacturer they would have one. Nesco www.nesco.com 1-800-288-4545

Possibly the bake igniter, the temperature sensor or the electronic oven clock/control. Does broil mode heat properly or does it run cool also? If broil heats to the proper temperature then the temperature sensor is probably ok. That leaves the ignitor or the controller which takes some more troubleshooting. If it is the controller, we repair them at www.fixyourboard.com.

I would suggest that you check the oven element, it sounds as though it is faulty to me.

Did you try going to the GE website? If not, try it:

http://www.geappliances.com/

When you pull up the website, you can click on the blue down arrow located in the box at the top of the web page, next to the work SEARCH and click on "USE & CARE MANUALS. Put your model number into the next box to the right and hit GO.

If you are having trouble after entering what you believe is the proper model/serial number, you can look at the FAQ (frequently asked questions) section to determine whether you have actually entered the proper number.