The Samsung message app is terrible and Samsung doesn't even install it on new releases. I would install the Google messages app and then when you click on the Google messages icon it will ask to make this your default message app - click yes. Follow the steps it provides to continue to set up. You will not lose contacts, etc and I've tried many ways to delete this app but it's one of those apps Samsung doesn't let us delete so I took away all the access, turned off it's ability to use mobile data, etc. Here's a link on how to do it which might save you time in having to go to yourour local store.
This is a pretty good video on installing and how to change options, etc.
