params.yaml - do the settings do anything?

[leeoades]

Hello,
I'm a complete noob so please forgive the (no doubt daft) question.
I'm trying to adjust the primary colour and setting it in params.yaml does not seem to override it.
Also, a lot of the other settings in params.yaml don't seem to affect the site either.
Is this work in progress? Am I doing something wrong.

In addition, I have set up a blog page but each blog article is rendered with a massive version of the small image I'm providing.

Hoping you can help,
Thanks,
Lee.