Drywall tape shows through paint

you will have to repair the dry wall before painting.most likely it needs to be lightly sanded down, primed and re-painted

You have to Remud to do it properly. You could put up a trim board over the seam, try to make it a design element.

I would remud it. Even do over the paint. Don't forget to prime before final painting.

First scrape any loose portions off, then apply mesh tape over the seam, and skim coat over it with joint compound, sand, prime and paint. There are lots of videos how to do skim coating and drywall repairs.

Ophs, videos on YouTube.

Yes. Then sand it smooth, prime & repaint

Go to Lowe's they have small tubes of pre mixed drywall mud. Put it on with a putty knife. lrt it dry all the way through. Sand it just slightl. Then when it's smooth an you see no more tape. Primer over that, then paint it. Hope this helps