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From the Organization Settings, the "User Authentication Settings" allows you to select the authentication method between 3 options: email & password, Jira OAuth for Cloud, and for Server/Data Center.

User Management

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Setting permission Levels

There are two permission levels - “Edit” and “Read-only”. They have separate limits from the licensing standpoint, which can be seen in the organization settings:

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• New self-registered users default to the “Edit” level if the seats are available and to “Read-only” otherwise.
• When a customer administrator tries to register an edit-level user while the number of edit-level seats for the organization has been exhausted, the red tooltip will display and clicking “Register User” will require confirmation for “Read Only” switch
• Blocked users do not count towards seat limits.

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Within license limits, you can set the permission level per user at "Edit Permissions" or for the whole organization using this checkbox column. 

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