If you tried everything in the AV1/AV2 thread for the STR-DG800 and STR-DG1000 receiver and remote, and nothing works, then it's possible, but unlikely, that Sony didn't provide for a command code change in both the receiver and remote for the STR-DG910.

I went through the entire manual, page by page, and didn't see one word about changing either command code. This is nothing new because if you look at the thread you will see several remotes where readers reported the procedure, which wasn't in the manual.

When you are sure you have tried everything, then we will have to conclude it can't be changed or there is some new method that may be hard to identify.

As for the discrete codes, you can find them here [Link: hifi-remote.com]

Then, click on Setup Codes and click on amp to find the codes for the Sony.

Then, click on Advanced Code List and check out each code for the Sony and see which one is the best for your purposes.

Of course, if you can't get the darned receiver to change to AV1, this won't help.