If a security in your Quicken portfolio is mis-paired with an online security, there's an easy fix.
Edit the security and unclick "Matched with online security".
Go to the Online center, select the Financial Institution and account containing the security, and click the Holdings tab.
Click Compare to Portfolio.
The dialog box will come up and allow you to correctly match the online security with one in Quicken.
Probably a lot of people know this, but until I figured it out, I had to wait for another transaction in that security and missed the price updates in the meantime.