I updated several Accounts for a DoubleClick product to the same Google Account. How can I switch between them?

For most products, you can use the dropdown in the upper righthand corner of the page.

For DART for Publishers (DFP): From the main menu page, click Switch DFP Account to select which account you'd like to sign into. Also, you can select a default DFP Account, where you'll first be taken to after signing in from the main menu.