What are you recording? Are you recording stuff that gets soft and then loud, or is everything the same and you're still getting volume spikes? If that's the case then your interface might have an issue. Or it could be your microphone, etc. If you're recording vocals, for example, you should set the input volume on your interface so the loudest part you're recording doesn't clip.
It could be a problem with my interface, because I'm only recording synth stuff, and it even if the stuff is almost silent, it gets louder and stays clipped for about 3 seconds, then fades back down to almost nothing. Don't think that's normal. But also, if I plug speakers directly into my synth, this weird volume thing does not happen, which is why I thought it might be a problem with my mixer. I'm going to try plugging my synth directly into the interface and not using the mixer. I'm hoping that will get rid of the volume changing.