How do I change the default permissions on my calendar?

Your calendar has a Default permission applied to it - typically this permission is set to "Free/Busy" (people can't see details, but can see blocks when you are busy/tentative/free) or "Reviewer" (people can see details, but can't edit).

You can then add additional permissions per user (example: Ron Swanson can have Editor access while everyone else has the Default permission of Free/Busy).

Why would I want to do this / How do I do this?

We wouldn't recommend changing the Default permission to anything beyond Reviewer or Free/Busy, but if you want to give everyone in your organization access to view your calendar details for scheduling purposes*, you could change the Default permissions to Reviewer. Here's how:

1.  Navigate to your calendar. 
2. With your calendar selected, in the Home ribbon, click Calendar Permissions.
   
   
   
3. Click Default in the Name column to select it, then adjust the Permission Level below by selecting the desired permission level from the drop-down menu (in our example, we would want to change it from Free/Busy time to Reviewer or, alternatively, Free/Busy time, subject, location). You can also make additional adjustments using the other options displayed (the options will change depending on which Permission Level is selected). 
   
   
4. Click OK. 

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*Example: Let's say executive assistant Ron Swanson has Editor access to your calendar, but your calendar's Default permission is set to Free/Busy. If Ron Swanson uses the Scheduling Assistant to schedule meetings with you, he will still only be able to see your Free/Busy times, no details. Unfortunately Scheduling Assistant only uses the Default permissions, not additional individual permissions.