Parsing dates in templates

I’m new to Hugo and don’t really understand the DateForm parameter (in the config file).

In the theme, I have: {{ .Date.Format .Site.Params.DateForm }}.
In the config file: DateForm = "02 Jan 2006".

That displays the date as “Sunday, Jul 19, 2015”. Oddly enough, when I remove the DateForm parameter from the theme, it works correctly:

In theme: {{ .Date.Format "02 Jan 2006" }} generates “19 Jul 2015” on the website.

How can I use the DateForm parameter so it outputs “19 Jul 2015”?

Edit: DateForm seems to be working now after I’ve restarted the Hugo webserver a few times now. It seems that changes in the config file aren’t picked up while Hugo is running.