Since you found the You Tube video on adjustment, look in the other recommended videos for you, there should be one for cable installation, also. You can make sure that the installation is done correctly. Their videos are really handy, for most any maintenance procedure you can think of, subscribe to a few for future reference.
As said above, congratulations on your wife wanting to begin riding with you, it will be time well spent.
Bill
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Semper Fi, USMC, 1975-1977
I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13