I have just changed email of my staff to access for the same account but it is having trouble with account not associated with this email.

Hey there, Sombo.
To make sure everything looks right on our end, I recommend contacting support. They will be able to authenticate you and assist in making sure the email you're speaking about is connected to you're account. Some times the email you're speaking of may be attached to a second account. We can check and make sure this isn't the case.  If you have any other questions, please reach back to me here.

Thanks for the reply. I am not sure which email to send to support as it's showing unavailable and asked me to post to community. 

Hey, Sombo.

Thank you for following up with us. You can follow this link here, to reach support. If you can't contact phone or chat support, let me know.

Hi, 

Thanks, I have emailed them since yesterday night and still have no respond.