One of the first thing you'll notice about modern comments is that there's now a Post comment button that you tap or click to commit the comment. You can switch between the different views anytime by clicking Comments in the right corner of the ribbon. If you reopen a resolved comment, it will be visible again in the contextual view.
You can interact with comments in the Comments pane the same as you would in the contextual view. To view all comments, including all resolved comments, open the Comments pane by clicking Comments in the ribbon.
This contextual view hides all resolved comments so you can focus on active comments. When you select a comment, a border appears around it and its position is closer to the page. In this view, all active comments are visible in context. When you add a comment in Word, you'll see it appear in the right margin as close to the insertion point in the text as possible. Modern comments aligns the commenting experience across Word platforms and other Office apps, especially Word, Excel, and PowerPoint. The modern comments experience in Word sets the stage for richer collaboration by your team and enables features such as notifications. In Word for Windows and MacOS, it's available in Beta Channel and rolling out to Current Channel (Preview) and Production. Note: This feature is currently available in Word for the web for all users.
