To log in to two Firefox accounts on the same computer, you can use Firefox's Profile Manager to create separate profiles for each account. This will allow you to run two instances of Firefox with different accounts. As for customer service in China, I recommend visiting the official Firefox support page or checking with your service provider for the appropriate contact details.

Dear mozilla support team

Thank you for your suggestion! I understand that I can use Firefox's Profile Manager to create separate profiles for each account and run two instances of Firefox with different accounts. Could you please provide me with a detailed, step-by-step guide, including any screenshots or instructions, to help me complete this process?

You can send my email, Email [edited email from community support forum]

Your assistance is greatly appreciated.

Best regards!