Hello Belinda,
I found a thread which is similar to your concern, and I can see that there are some users was able to resolve the problem by following the steps outlined in this link:
https://answers.microsoft.com/en-us/msteams/for...
If you are looking on how you can customize the Appearance in Microsoft Teams, please check this as well: https://support.microsoft.com/en-us/office/cust...
I hope this helps, let me know if there's anything else I can help.
Kind regards,
Jayzar