This content only applies if you're using Fusion for education.
Once you create a milestone for a version of a Fusion design, you can edit its name and description.
In the Fusion Data Panel, click the version drop-down in the lower right corner of the design’s thumbnail.
Hover over the milestone you want to edit and click More
.
Click Edit Milestone
.
Edit the description and milestone name.
Click the checkmark button to commit the changes.

the Fusion web client, in the navigation panel, open the detail page for a design that requires a milestone change.
Click the version selection drop-down for the design.

Select the milestone version of the file that you want to edit.
Click on the ellipsis in the upper right and select Edit Milestone
.
Revise the version description and milestone name in the Edit Milestone dialog.
Click Update or press Enter to update.