$1936

Just finished my first Alpha bracelets and there's straggly threads at the back - how do you guys glue/cover them to keep them looking tidy?

Alphas are never really tidy on the backside, unless it?s a two-colored alpha that uses the base-strings for the second color.
I always glue the string-ends with tacky glue.

I used superglue stupidly and the back would be rough on skin because it?s ?crunchy? where the glue has dried. Would normal fabric glue work just as well?

Yes, but it?s thinner than tacky glue so you must be careful to not let it run through the bracelet and show up on the good site. That?s why I prefer tacky glue. But fabric glue is probably better washable.

You could possibly glue or use an adhesive to attach a piece of fabric or felt to the back of it. It would have to be cut out the exact dimensions of the bracelet.