You would think this could be a solution, because it certainly appeared to be. But far far back on this topic, as in 2 or more years ago, I believe it was reported that it didn't work, and that Intuit manages to overwrite that setting, connecting your QB desktop to the Internet by force, and you're back to signing in with 2 IDs and 2 passwords for each and every desktop version entity. I know it was overwritten on my desktop. The only way I've avoided the double sign-in, Internet exposure, and Intuit harvesting of my companies' data for 2 years was to make changes through Microsoft Windows Defender Firewall using 2 inbound blocking rules and 2 outbound blocking rules. The rules tell Windows to prevent the QB .exe files from accessing the Internet by blocking a TCP port. Someone was nice enough to write up specific instructions somewhere among the incredible 29 pages of complaints and useless responses from Intuit personnel about how we're all being protected. 

This method won't help if you use QB payroll, bank access, etc., since it blocks all Internet access before QB even starts up.