A simple guide to choosing the proper caulk

 https://www.youtube.com/watch?v=jkiCJ-Lv4Oo

In summury,

95% of the time, choose dynaflex 230, good for windows, gutters, siding, doors, trim, flashing, composite wood and pvc trim board.

5% of the time, choose silicone caulking, eg for bathtub.