Content Modification Interface in your SuperSite 2 / PartnerSite Admin Always Opens Only in a Specific Editing Mode

The Content modification tool would, by default, open in the Basic editing mode if the file contains any text that can be edited/translated; otherwise it would open in the Advanced editing mode.

If you save changes in a particular editing mode, then it becomes the default editing mode for that particular file, and the interface would automatically open in this edit mode thereon (for that particular file only).