Note: We've just updated the name of "Match Type" - it's now called "URL Scope".
See here for a full overview of exactly what our URL Scope (aka "match type") options mean.
How to configure URL Scope to change rankings match type
From within a campaign, click "Settings" on the bottom of your left side menu.
The match type can be configured by changing the "URL Scope" setting.
When you're done, click "Save" before leaving the screen.