New bookmarks show in dropdown search box in SharePoint after months

Hello,

In the last year or so I have created dozens of bookmarks via 'Search & Intelligence'. The bookmarks are immediately visible in the search results of our SharePoint intranet. However the bookmarks also show up in the dropdown of the search bar, my experience is that this can take many months to become visible. Any changes, for example in the name, sometimes also take months to become visible. 

Does anyone know how I can get these bookmarks in the dropdown to become visible/process changes faster? Or, even turn it off? 

Bookmark shows in search results immediately after publishing

Bookmark becomes visible in dropdown search bar after random amount of time