Rename existing page / change "site_title"

cms-pico is really great! thanks for sharing!

What I could not figure out is: How could I change the “site_title” – the headline, which appears at the top of the page and is initially entered while creating the page?

Any hint is welcome!

Thank you in advanced,
cheers!

I am referring to this (sorry for having this only in German):

I have the same question/problem. I tried to use a custom config.yml (like described here), but putting it in a config directory in the root of a (Pico-)site (next to ‘assets’ and ‘content’) doesn’t do the job.