I've searched this forum but haven't found this issue yet.

For example: Column A has either a 1 or a 2 as the cell contents. Column B
has a bunch of various values. What I'd like to do is to Find and Replace 1
with 2 (or vice versa) but based on the contents of Column B. I can't do a
simple Find and Replace with Column A because then all of the 1's will be
replaced with 2's.

I've looked all over the place and I can't quite seem to find a solution to
this. I can of course alter everything manually, but I'm dealing with 350+
sheets with each sheet containing 2500+ rows.