@Grumpyoldfart
When you get to the Reply window, click on the A/A box in the top right-hand corner; the background will change from pale yellow to white, and your troubles are over.
OK, I clicked the A's in the RHC, not the LHC (which is what I had actually tried) and IT WORKED! All I have to do now is figure out how to default to that mode.
Many thanks for that tip and thanks to all for the efforts in helping.