Permissions dictate what a user can do in One Church Software. Grant permissions to each individual person (including whether they have access to administrative portions) from their person profile.
To manage these permissions, you would go to the person's profile and click on Actions > Manage system access in the top right. Note that this option will only appear if they have access to the system.
You can also get to the same place by going to Settings & Tools (the cog) > Security > Users tab from the top navigation menu. Then, go to the 3-dots menu beside the desired person and select Manage permissions. The User Permissions pop up appears. Make the desired changes and click on Save.
Next Steps
Learn more about the different between guest and super user access.
Read this collection of articles to learn more about each permission.