Hi pmr,
No, even if you have transported the query from Dev to QA, you will still be able to change the query in Dev anytime. The Transport shouldn't be the reason you are unable to modify the query in Dev.
However, depending on the system landscapes, certain environment, you need to create a BEx Transport in order for you to modify query, any query for that matter.
Try this:-
got to T-code RSA1 > Transport Connection.
Note upper setions, you will notice a button with a "lorry" with the Word "BEX".
Click it, and a window will prompt, click on "assign/Delete" button, and Create a new transport: Bex Transport.
And try to modify your query again and see whether this works.