In SharePoint Online within the Administration Center, I can go to Search Center Settings and set a Search Center URL. I can do the same thing in the search service application for an on-premise instance of SharePoint 2013. I want all of my site collections by default to use this search center and this is the place to configure it.
This works great if I want Results.aspx to be the default page in my search center, but I do not. I have a custom page that I have added that I want to be the default page, but I don't see where I can make the setting to have all site collections use this page without visiting the configuration on each site collection.
I suppose I could rename Results.aspx to something else and rename my custom page to Results.aspx, but it seems like there should be a better way.
Is there a way to change the default page from Results.aspx to something else and only make this setting in one place (the search center)?
EDIT: FWIW, I looked at the SPWeb.AllProperties on a search center in my on premise SP2013 and didn't see any web property that indicated the default page was Results.aspx. There is a "__DefaultPageLayout" set to "_catalogs/masterpage/SearchResults.aspx", but I'm pretty sure that is not the answer. It could be that there is a web property for this whose default value is Results.aspx and can be added to be changed from the default. For that I might have to use a bit of reflection but it might be a dead end.