The 601/709 import setting only determines the source color levels, not the frame size.
Project type determines the frame size of anything and everything you bring into MC.
And even when exporting to an external drive, you will not want to blow them back up. You have scaled down the HD sources to SD, and now they are no longer HD (the sources are, your mediafiles in Avid are _not_). Exporting them to a bigger frame size will not make them look an inch better; perhaps even worse.
If you want to do this correctly, flip your project format to the appropriate type (check the sources if they are 702p or 1080i or 1080i). Then Batch Import the source files. Then everything will be HD, and you can export as HD.
With CTRL-9 or CMD-9 I mean the Ctrl-key on your keyboard (PC) or the Command-key on your keyboard (Mac) and the ‘9’-key on your keyboard. It’s a shortcut that takes you to the Project Window (also under Tools menu).