You can change your account's username and profile picture's directly from GlotDojo's account settings. To do this, please:
Step 1: Go to GlotDojo website.
Step 2: Select the profile icon in the right corner of the screen
Step 3: Select Account Settings
Step 4: Type in the Display name and the new Username.
Step 5: Select Save to save the new username.
Step 6: Click Change Avatar to replace your avatar.