Scarves come undone!

I have a rectangle loom and have made about 20 scarves-- but every one of the ones I give my grandkids comes apart at one end. Of course, I have watched videos and researched to see what I am doing wrong. I finished a scarf last night, beautiful finish on both ends and my granddaughter handed it to me after church with the end all undone. WHAT AM I DOING WRONG!!!

Welcome to KnittingHelp!
How are you finishing the scarves? Are the individual sts coming out or is the finishing strand unraveling? Are both ends undone or only the final bind off?
This is a common method and it seems to work well.

I will try that method if I do another scarf. I am so frustrated. I have done this method:https://www.youtube.com/watch?v=wNvEnbx6Jw8
and then the one you shared but I did not do the yarn weave at the end. Maybe that is the problem.
I am hoping to fix her scarf later today by re-attaching it to the loom and trying again.

THANK YOU

Well, that looks like a reasonable way to end but I couldn’t see how the final stitch was tied off. Definitely pull the yarn end through the final stitch and weave in the tail. Make sure the tail is 6-8inches after all the sts are bound off so that you can weave it in and them maybe go back and weave it in the opposite direction. Good luck with it!