Sometimes it can be necessary to restrict sets of reports or templates to specific groups of users. Perhaps you don't want the purchasing managers being able to the financials area etc...
Even when using user groups properly, this can be still time consuming to do in the web interface if there are many items that need to be updated at once.
However - it is worth noting that this can also be done through the Designer interface which has the ability to select multiple items at once and bulk update them.
If wanting to set permissions on templates, go to the "Advanced" tab and click "Export Templates":
Select the templates to change permissions by shift clicking the items you require. Then right click, and select "Change Permissions":
Then use the permissions dialog to restrict users and groups on all items at once, accordingly:
Similarly, permissions can be set on multiple reports or folders at once. Instead of using the "Export Templates" button, select "File->Open" from the file menu:
As with the template example above select the reports and folders that you wish to change permissions on, right click and select "Change Permissions..."