Depending on your portal's set-up, you may be able to add a new role. For example, if you are a mentee and want to also be a mentor, you can add the mentor role.
You may notice that when switching/adding a role, the options are grayed out. Once you are assigned or select a role, the only way to remove the original role is by requesting through your program admin. You cannot remove a role yourself, only add a new role.
If this is enabled in your portal, you can go to your matching form (maybe called "Matching Questionnaire" or "Apply to Program" or some variation) and select which role you would like to add. You will then be required to take the matching questions survey for the new role.
If you are not able to add a role or wish to change roles, please contact your portal administrator for further support.