I am having trouble getting my muffins to rise. I made sure my baking powder and baking soda were fresh.

I am wondering if it is my oven. all of the recipes say to bake at 375-400 degrees fpr 20 minutes. i have a convection oven and was told i should dial down the temp by 25 - 50 degress. i have tried numerous settings on other food and they cook to quickly and over cook. i have tried lwering the temp by 50 degrees and cooking longer. this has generally worked better.

I am just looking for any assistance available. i ould be crazy and the oven has nothing to do with it.

all assistance will be greatly appreciated.