I hope you are using a good cleaner, that is the key to getting old
cedar its best. If its not to late and you have Shrewin Williams nearby
get their cleaner, Ive seen jobs that only SW cleaned best. For the mold
it depends on what your cleaner contains or household bleach kills it
and its cheap, I just use Bleach.

Thompsons is one of the worst products, Consumer Reports has an ongoing
test of stains and sealers, and dropped Thompsons because it cant
compete, get their article before you decide, a natural colored
Transparent stain will get you many more years then clear. Spend time
cleaning it right and picking your finish, Cabots is always good but a
clear finish is yearly maintenance.