After much hair-pulling and frustration, I discovered on my own the solution for how to retain wanted cookies while getting rid of the unwanted ones. Here it is, step-by-step:
- On the startup screen - select "Privacy".
- Under "Select your action" - select "Clear Your Browsing History"
- "Browsers" from the left-hand side should be automatically selected. In the box, the browsers you use should show in black; non-used browsers are greyed out
- A blue line entitled "Select which Cookies you want to retain" will show below the "Browsers" box and above the three orange buttons. Select that line.
- A pop-up box will appear with all your cookies displayed. Choose the ones you want to retain.