When I download my banking transactions they duplicate my transactions in Quicken. OR they will overwrite my quicken transactions. What settings am I missing?
You need to explain a bit further what's happening.
In EDIT, Preferences, Downloaded Transactions … do you have either "Automatically add …" option checked? DON'T. Instead, the downloaded txn will appear in a window below the account register with a status of "Match", "Near Match" or "New".
A Match is paired with a transaction that you previously manually input, and will replace it.
A "Near Match", almost matches, but not quite. You should research why it doesn't match (probably the date), and correct the previously input.
A New will create what might be a duplicate, or might truly be new. If you think it should have been matched, you need to research why it didn't (possibly date, possibly you mistyped the amount) and correct the prior input.
Then Accept the transactions in that download pane ONLY when they Match … or you've determined that they are truly new.
P.S. If you're really running QW2017, as your profile states, you shouldn't be able to download anything. That product was sunsetted 6 years ago … so you might want to consider updating your profile
@Jim SP You may be seeing the problem discussed here
If that is your issue, please add your comments to that discussion.