Short version / TLDR:
If you want to change MFA, you should use Microsoft 365 portal (office.com) and change settings of the account (p. e. phone number). More information can be found at
A little longer
Check 3 links:
- Troubleshoot Azure subscription sign-in issues - https://learn.microsoft.com/en-gb/azure/cost-management-billing/manage/troubleshoot-sign-in-issue - some causes of problems is sometimes can be easy to check
- error codes can be find here: https://learn.microsoft.com/en-gb/azure/active-directory/develop/reference-error-codes
- 50074 error code states that you've got problem with MFA - due to "AADSTS50074 UserStrongAuthClientAuthNRequiredInterrupt - Strong authentication is required and the user did not pass the MFA challenge"
- and about Azure AD Multi-Factor Authentication itself you can read at https://learn.microsoft.com/en-us/azure/active-directory/authentication/concept-mfa-howitworks
Maybe in previous job some of "Available verification methods" (p.e. sms/Microsoft Authenticator/OAuth Token) were used as a additional forms of verification? Then use office.com portal and change user settings with link mention above: https://support.microsoft.com/en-us/account-billing/change-your-two-step-verification-method-and-settings-c801d5ad-e0fc-4711-94d5-33ad5d4630f7