How far did you get with the steps?

Open Firefox and make sure you are signed into Sync (open the "3-bar" Firefox menu and look for your email address instead of "Sign in to Sync"). Go to https://accounts.firefox.com/settings?canChangeEmail=true Visiting this special URL will make the feature visible. Under Secondary email, add another email address and click the Add button. Follow the instructions in your verification email to confirm your second email address. Refresh the page and the "Make primary" button will now show up under Secondary email.

• https://accounts.firefox.com/settings?canChangeEmail=true

Click the button to change this to your primary email address.

I went thru all the steps, trying multiple times.

The button that was supposed to appear to make my secondary email primary never did.

Do you see the Secondary email section and the button to add a new secondary email address on the settings page?

• https://accounts.firefox.com/settings?canChangeEmail=true

Oops, I missed your above reply 30 seconds before mine.

You will only see this section and button if you are connected to Sync on that specific device and you see the email address in the "3-bar" Firefox menu button drop-down list. If necessary then reload the page.

Everything was logged in and synced properly, I reloaded the page over and over, closed and reopened it, and still nothing.

Try to click the manage account button on the about:preferences#sync page.

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems