how do i make a member an owner in a team?

Dear @Fiona Kimberley-Pope,

Good day! Welcome to Microsoft Q&A forum!

Regarding your situation, if you are already a team owner, you can typically promote a member to an owner by following these steps:

• Open Microsoft Teams
• Select the team and click More options (⋯) next to the team name
• Choose Manage team
• Under the Members tab, locate the user you would like to promote
• In the Role column, change Member to Owner

For reference: Make someone a team owner in Microsoft Teams

If the option to change the role is unavailable or you encounter any issues, please let me know what happens when you attempt the steps above. I'll be happy to help further and suggest the next steps.

Any updates you’re able to share would be really helpful.

Thank you for your kindness and patience!