How do. Stop the paint cracking here?.

[Fluffycloudland77]

This is the top of the wood that joins the stairs to the wall, it’s cracked again 🤦🏻‍♀️ We’ve filled it with flexible filler before but it just comes back.

Tell me what to do and I’ll do it.

No advice but mine is the same so following with interest! So annoying, I sympathise.

Is it humid where the crack appeared? Any condemsation or damp? If so fix that then patch it (ie fill it with wood board, glue, then sand and oil / varnish). The guide below is fairly good if it’s a similar staircase?

homeguides.sfgate.com/fix-cracks-wood-stairs-29539.html

Caulk. It expandable in some way. For exactly this sort of thing.

Definitely caulk

Use caulk to fill in the cracks, wipe any excess off with a cloth. It will dry Matt so you will need to paint over it once dry.