Thank you so much for the answer...
First - constrain proportions lock is unlocked. I was able to reset the width, but then when I tried to reset the height somehow it resets to 3.0" instead of the 3.5" I specified.
Second - I'm on an iPad Pro, so its seems to work a little differently. Resize canvas doesn't look like your example. I try to reset the units by choosing Resize, following the right arrow to the hidden dialog box, choosing "inches,", going back to the first dialog box and applying. Nothing. I also tried changing the dpi to 300 and the sampler to Lanczos3 with the same result, nothing. I also tried changing units to inches on the first dialog box, in the width adjustment box, with similar lack of success. Very little I do here "sticks" after applying.
Thanks for your help, I'm baffled...