If users forget their password and don't know how to reset it, you can either reset it as the admin or you can explain how they can reset their own password on the storefront.

To reset the password as an Admin, navigate to the People tab, then under the second People tab, find the user you need to reset the password and click Edit. Select the General info tab and scroll down to the Privacy section.

You can set a new password and then share it with the user, or can also send a reset password email or obtain a reset password link for the user and provide that to the user directly.