The email address that's displayed on your invoices is picked from your organization profile. So here's how you can change your email address:
1. Click the Settings tab.
2. Under Organization Settings category, click the Organization Profile link.
3. Change your email address that you want to be displayed on all your invoices, and then click the Save button when you are done.
Now, all your invoices will have the new email address.
Zoho Invoice FAQ