To make changes to a document in Reading view, in the upper-right corner, select Edit Document > Edit.
If someone else created the document, they might not allow editing. You can go to File > Create a Copy, save it with another name, and edit the new document. Or you can ask the document owner to enable editing.
You can do these simple tasks in Reading view:
- View and add comments
- Share a document so you can work together with other people at the same time
- Download a copy