I've gone to the "default app" screen and the only app I can make default is Samsung messaging, before I could use F.B messenger and it combined my Facebook messages and my SMS. Anyone else having this issue and/or found a solution?
For those who are looking for a crossplatform messaging app, I would highly reccomend Signal. You can set it up in less than 2 minutes and it will automaticaly find other Signal users in your contacts. It is privacy-respecting and has clients for Windows, Mac and Debian-based Linux operating systems.