Hi Sunshine1,
A user without the Word desktop application can refer to the following steps to modify a Word document and save the changes in team site.
1. Click the menu of a document and select Edit in Browser.
2. After editing this document, click Save in the top left. The changes will be saved directly in the team site.
3. Close this document.
@ Robert and mchv2.0, we appreciate your efforts.
Thanks,
Kevin Cui