Hi ai_ling
Thank you for the update.
Is the company file you are accessing online? If so, there are two level of access you need to use:
1. Online access, this is done by logging in using your email address & password.
2. File access, after entering email address & password then select the desired company file to open, you'll need to enter an User ID & its password. This ID determines your permissions to different functions within the company file.
By default each company file has the user ID ' Administrator', it starts with no password. So as mentioned, when you or your senior open the company file, please be sure to enter the user ID 'Administrator' & its password. Once in, go to Setup > User access, select the relevant user ID from the left, then check the role(s) ticked for that user ID. For the user ID 'Administrator' I'd suggest only tick the Administrator role and nothing else.
If you only need to enter email address when logging in to the online file, it's because that the person invited you to the online file has linked an user ID to your my.MYOB email address, and you don't need to enter user ID during log in. In this case, please do have the person set up your access to log in using Administrator user ID to check roles assigned.