In every situation you can flag items as especially important. These items will be shown first in the lists and have a red flag. The same applies for Projects, Folders and Meetings. If you flag them they show up on the Review tab so you can easily access the most important projects without browsing through the large pile of stuff.
Flagged Items are shown first in the task lists.
Tap the accessory button next to the project you want to flag/unflag (1). This opens the Collection Popover. To change the Flagging tap the flag icon to flag/unflag an item (2).
Flagged collections (1) (Projects, Folders and Meetings) are shown additionally on the Focus tab(2).