O365 edit online

 

When you open an Office document from OneDrive the document you may notice you are not able to edit the document. The document is in Reading View.

Edit

Notice the menu options along the top to switch from Reading View to being able to edit online. You can also choose to edit the file in the desktop version, which will open up full editing functionality to you. The online version is limited functions, but is collaborative and in the cloud.