Oven door leaks heat

You need a new door seal. Get the oven make and model number to order the correct one. There's also a possibility the hinges need adjusting so the door closes tight.

Is there not a seal on the inside of the oven door going all the way around. Yes those hinges how they are adjusted would depend on particular oven. What's the make and model.

Don't do that, just replace the seal itself. It's a quick and easy job, even for someone without any experience.