@andrewc2340AndrewC2340
RE: Download invoice and email manually - you would need to open the invoice you wish to send, then go to Print, choose your form (probably the first option), then in the Print dialogue box (General) choose "Print to PDF" as your printer, then save the invoice on your hard drive or other storage medium in an easy to find folder. This PDF file can then be attached in an email to the client. You won't need to do this if you have verified your company details for Secure Invoicing.
Also, once you have verified, the Secure Invoicing feature cannot be turned off - it's the Online Invoice Payments option that you may wish to choose to opt-out of. The fees charged for MYOB to process your online invoice payments are not worth it in my opinion (and many others' opinions), but unless you have an issue like using a 3rd party software to synch invoices or you do a "copy invoice" to create new invoices, the system-wide online invoice payments feature can be turned off, and it won't affect your ability to email (share) invoices - once you have verified!
My main gripe with this "mandatory upgrade" is the bundling of secure invoicing with automatically enabling online invoice payments through MYOB. That should have been a separate and optional step after verifying. But that wouldn't have grabbed as many users into the fee-earning online invoice payments system that increases MYOB's revenue (they hope!)