Do not forget to update to Microsoft Office 2013 when using Office 365 or SharePoint Online

When deploying a published SharePoint 2013 on-premise installation or a Office 365 installation or a SharePoint Online installation, it’s highly recommended to update your Microsoft Office 2013 installation.

There are some minor perks as these:

• Access 2013: new application model
• Active Directory-Based activation
• Apps for Office
• Click-to-Run
• Click-to-Run customization
• Co-Authoring
• Downloadable proofing tool packages
• New Group Policy and OCT settings
• New Visio 2013 file format
• Telemetry Dashboard and Telemetry Log
• Office Web Apps
• Office Web Apps Server
• Security changes
• Sign-in IDs
• SkyDrive Pro
• Additional resources

But the most important change you’ll find in the “Security changes” section.

• Security changes

• Authentication in Office: With Office 2013 you don't have to provide your credentials to edit a document from a online SharePoint installation. Microsoft Office 213 stores your credentials and provides them when needed.