Once a report is embedded it cannot be edited. You must disable embedding for a report in order to edit it.
to see embedding status:
| rest /services/saved/searches | table title,author,embed.enabled
I agree that this makes no sense (that you cant edit a report or its query if its embeded some where).
but if that is required, then the number of pages and hoops you have to jump through just to change the query of an embeded report is un-reasonable. (and they are all on different pages / sections).
we have some reports embeded on status monitors (ie PRTG maps), and from time to time have to change a query, and its always way more difficult than it should be (and time consuming)
this needs to be improved, splunk.