Doors don't shut all the way and light stays on

It sounds like your door hinges are worn, usually on older ovens due to weight of door. Most oven doors can be removed by simply raising the tabs/ fitting small screwdriver on both hinges(refer to user manual) etc. Once door is removed you can place a medium size screwdriver or similar in the hinge slot, pushing the hinge plate on the bottom in an outward direction, thereby bending this plate(very slightly) forward. This will make the door close fully, activating the door switch, and turning off the oven light. This is only a short term solution, as this hot air escaping can lead to further problems. Hinge pair will need replacing. Door hinges are spring loaded ALWAYS KEEP FINGERS AND HANDS CLEAR OF LOADED HINGES.