Here's how you (and your students) can add preferred name and make other customizations to the way your name is displayed in Moodle (such as adding preferred pronouns):
1. Open your Moodle Profile:
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2. Select Edit Profile:
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3. Type to add the preferred name to the Preferred name field:
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4. Scroll to the bottom and select Update Profile:
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Your Moodle Profile will be updated to display your preferred name.