Can't make GO SMS default txt app

[Muppet Rat]

I've installed GO SMS, force stopped & disabled the stock message app and GO SMS still isn't showing up in the option list to set as default. With the stock app disabled, all it shows is Hangouts, and with Hangouts disabled, the list is empty. I would just ignore the stock app, but I'm getting a persistent notification number on the sms icon on my lock screen until I open the txt in the default app.
My phone is NOT rooted.