How to make my forum skip a line when typing (WBB 4.1)

Hello everyone, for some reasons it seem, i can't skip a line when typing/writing a post.

It's quite problematic, how can i fix this, it's the legacy version 4.1 by the way (i won't update).

Here's a picture.

pls help.

Resolved it.

Here is what worked for me : deactivate "Enable HTML" in System - Options - Messages.