Carb Manager can automatically adjust macros as you log exercise if the Deduct Macros When I Exercise setting is enabled. This allows you to eat more food, while still hitting your goals.
To enable that setting, open your main (left) navigation menu and select Settings.
Then, under the Settings tab, scroll down to the Carb Manager App Settings section, and Macros Settings subsection. Once there, toggle the Deduct Calories When I Exercise setting to On.
Once this setting has been enabled, the Deduct Macros When I Exercise setting will appear (you must deduct calories in order to deduct macros). Toggle this setting to On as well.