Microsoft To-Do now offers task assignment support for all users, which enables you to assign individual items to users within shared lists. Typically, this functionality would be used to indicate the person who's responsible for a particular task.
To use task assignments, you'll need to have a shared list in To-Do. You can follow our dedicated guide to get up-and-running with a shared list for your users. Once you've created your list and added some users, you'll be ready to assign them their tasks!
Select any task in the list to open its details pane. Next, click the "Assign to" button to open the assignation popup pane. Here, you'll see all the users who have access to the list. Click their name to assign the task to them. You can also assign the task to yourself, or share the list's link again to invite a new user.
Once you've assigned the task, the person's name will show up in the task's details pane. You'll also their profile picture back in the main task list, so you can see at-a-glance who's working on each item. To change or remove the assignee, just click their name in the details pane to get back to the "Assign to" prompt.