Change cookie lifetime

Hey guys,

I would like to change the cookie lifetime to 7 days. Unfortunately, I don’t know JavaScript well.
Hopefully someone can help me.
This is the Code in my Piwik Admin surface:

Here Piwik describes how to change the cookie lifetime, but the code in this example looks different than mine:

Moreover, I don’t even understand how the cookie is set in the above mentioned codes. I thought, cookies are set
by set.Cookie or similar.

Thanks for your help!