I had the 550 for a while, (hated it...screen too small and dim for these old eyes to see) but I seem to remember having troubles with the "A" & "B" buttons as well. Perhaps you can find a different unused hard button or create a soft one in the view screen. And indeed I did forget that once you change the state of the CC mode, you must save it before exiting.
The same is true for the Hopper. You must save the CC mode after changing it. Fooling around with it last night I saw that if it is in the OFF state, the cursor snaps exactly where it needs to be on "ON" so a complete one button sequence should work once the placement of the cursor bug is fixed.
It would then be: Yellow/3/Select/Select/Live TV.
The same is true for the Hopper. You must save the CC mode after changing it. Fooling around with it last night I saw that if it is in the OFF state, the cursor snaps exactly where it needs to be on "ON" so a complete one button sequence should work once the placement of the cursor bug is fixed.
It would then be: Yellow/3/Select/Select/Live TV.