Failed attempts at baking

Moving always requires getting adjusted to a new oven.  Our current oven -- like our washer/dryer -- is of the miniature variety.  It barely fits my medium cookie sheet.  I thought the biggest challenge to use it would be converting the temperature between Celsius (on the knob) and Fahrenheit (all my recipes).

Thanks mom for the ONLY holiday decorations in my house.
They barely fit, but there they are.  

But conversions aside, I haven't managed to bake anything without burning the top.

Cake.  Muffins.  Cookies.  All of it.

I made banana muffins with a butter/sugar crumble on top.  The top was literally crunchy and not edible. But the middle was perfect.   Anyone know the way to fix that?  Shorter time/lower temperature?  I might just give up baking, because it's not helping me make friends, and the charred calories aren't worth it for me.