popup text widget not updating

Hi! I have a custom website and theme based in twentyfifteen as far as I can tell. I have a popup on my site whose content (text and image) I need to update. I found a custom widget (text) which I believe is the popup, changed the text and URL to a new image, and it will NOT update! I did this hours ago, have cleared my cache and tried 4 different browsers. Two other text widgets are updating just fine. My themes, plugins and WP are all up to date. I already tried deactivating all my plugins and switching to accessibility mode. Still not updating. The new text and URL are saving fine, the changes just aren’t showing up on my site. I’m NOT a developer but I looked through the theme options and some of the php files and couldn’t find anything that looked like the popup (maybe it lives elsewhere and not in the widget?). My boyfriend has a computer science background and spent several minutes staring at the widget code and he’s stumped too. Help!