With nothing selected
Go to Object>Anchored Object>Options
Make your changes
There are two Defaults - first one if you're just copying and pasting from InDesign - make the change here and anything you paste into a text frame gets these defaults.
The second one relates to when you use the File>Place function when inserting from a file on disk
Technically you should set an object style too - that means the Anchored Object settings are inside the Object Style, and if you need to make global changes to your Anchored Objects you can do so with the Object Style.