Only Admins can change User Roles

From the Dashboard select Users (This is a back of site function, login and from the top drawer select Dashboard)

Search for the user to change Username and email address are searchable fields, the columns may be reordered to help you.

Once identified you can Edit the user details including the Role.
Usually a new member need to be promoted to Contributor / President or Club Secretary

It is not possible to edit the USERNAME if you need to do this the consider creating a new Username and deleting the old one.
The system will not accept identical email addresses for different usernames.

Do not forget to save your work.