Different Dashboards for Different Sites

I have four different sites that I run through WordPress- all of them are hosted through Go Daddy. I did not set up the hosting for two of the sites, but I have child themes that I created for the sites, and I’ve edited the CSS for those sites. These two sites (www.burlingtonbookfestival.com and http://www.eatingwithgrace.com) have what I consider to be the “normal” WordPress dashboard- grayish/blue color with the regular appearance, plugins, user, tools, settings, etc. tabs in the left menu.

However, my other two sites have a completely different dashboard. It is black, has a store tab in the left menu, and has no plugin tab, as well as a few other differences. I never really paid much attention to it for my personal site (www.melindaversesprose.com) because I do not have a child theme for that site, nor do I make any changes to CSS on it. However, I just created a new site (www.dookuniversity.com, which doesn’t have any content yet), and I want to customize the CSS for it. However, I’m unable to figure out how to use a child theme (which I created in my go daddy account) for it, or even how to edit the CSS. I bought domain mapping through WordPress for these two sites, and I’m wondering if that’s causing it to have a different dashboard and is disabling some of the features, such as the CSS editor? For both of these sites, I purchased the domains and hosting through Go Daddy, changed the nameservers to point to wordpress, changed the URLs in WordPress to the domains I bought, and then purchased domain mapping through WordPress. They had the normal dashboard when they were .wordpress.com sites, but are now different.

Does anyone know why these dashboards are different, and if/how I can get it back to “normal?” Thanks in advance.