A lot of Outlook users like to use flags to keep on top of their commitments, with the flags letting you know when to return to a specific item – later in the day, or even a week away.
It can be a hassle to organise the flags on each click. But if you set a quick click, you can make the flag be the same type of category when you click next to the message every time.
Click the “follow up” button at the top of Outlook, then click on “set quick click”. There, you can choose what type of flag appears when you single-click the flag column next to a message.