First, go a little further than clearing the model, start a new model. 'Clear' may have different meanings. It doesn't necessarily mean 'set to factory defaults,' but for instance might mean 'set all -values- to default.'
This started with an arming issue, yet later you're talking about pitch. It's supposed to arm with the yaw as is most common, correct?
The only thing I think that could cause crossing of yaw and pitch is a miswire between Rx and FC. Triple check all wires, or don't even think about it just pull them all out and start over.
I know you've done a model previously this is just a reminder. Pay no attention to wire colors but the order of the wires as they're plugged in from Rx to FC.
And to triple check, are you for-sure arming in a mode that doesn't rely on GPS? That topic has been common here lately.