Our SharePoint Online Master Page is using this code:
<SharePoint:DelegateControl runat="server" ControlId="PageHeader" AllowMultipleControls="false" />
To display the "PageHeader" with the login link. Some users on mobile devices do not see this link. And it has Twitter and Facebook links next to it that we need to edit. Where or how on the SharePoint Online site do we edit the "PageHeader" HTML?
EDIT: 5 minutes after posting this I found it in the Root Site "Site Elements" List.