Use the Glass Cleaner at it's recommended dilution level togehter with a microfiber polishing cloth. If this doesn't remove streaks, then there is an underlying problem.
The best way to apply #40 depends on the condition of the surface to be treated. #40 has a mild chemical cleaner it in to first help clean the surface of dirt and
grime. If the surface being treated is extra dirty, then first pre-clean with #39 Vinyl Cleaner.
If it's not to dirty/grimy, then apply the #40 using a piece of terry cloth towel. While applying,
aggitate the surface using the #40 as a cleaner/Conditioner. Wipe off.
If your towel shows dirt where you wiped it off, repeat.
The cleaner in #40 together with some aggitation from a piece of terry cloth should be enough to remove what ever you put on the surface the last time.
Mike