Xperia Z3 :: Messaging Not Default SMS App

Every few days I get a notification:

"Messaging not default sms app. Tap to make Messaging your default SMS.."

(that's what it says; it actually stops mid sentence). I click on it and there's a dialog box:

"Change SMS app?
Use messaging instead of Hangouts as your SMS app?
No Yes"

Now obviously I don't want to do this (why would anyone), but I click on No and the box goes away but it'll come back again later. I can't uninstall messaging, and when I load it to see if it has options to never do anything again ever the first thing it does is pop up the "Change sms app" box again, and when I press No it quits.