Ads not displaying in the same space on every page

I use Google Adsense and put the code in so the ad displays underneath my post title on single pages. However, I noticed that if I click on the pages in my Nav Bar, the Google Adsense ad displays above my header on the About & Advertise page. I’d like it to display underneath the page title, but cannot figure out how to do this on those two pages. It is showing up correctly on every other page, so I’m not sure why it is doing this just on those two pages.

How can I make it so the ad shows up underneath the page title on my About & Advertise pages only?