The Back button only works if you open a link in the same tab. If you open a link in a new tab then you need to close that tab or select that previous tab if you want to keep that page accessible.

Use this to open the tab history list:

• Right click on the Back or Forward button
• Hold down the left mouse button on the enabled Back or Forward button until the list opens

You can look at this extension:

• Backward Forward History Dropdown: https://addons.mozilla.org/firefox/addon/backforedrop/

I don't think you understood the question. I am having the exact same issue. I open a link in a new tab or window, for example: https://addons.mozilla.org/firefox/addon/backforedrop/

When the new tab opens, I click on "reviews" to open the link: https://addons.mozilla.org/en-US/firefox/addon/backforedrop/#reviews in the existing tab because I want to see the reviews for this feature. After I read the reviews, I want to go back to the main link, but the back button on my browser is greyed out, as though I was never even on the previous page. So my options are 1) Open every link I ever click on in a new tab or window, or 2) Hope the website is user friendly and attempt to navigate back to the previous page using links inserted on the current page.

You never realize how frustrating not having back button is until it happens.

Just found this post:

https://support.mozilla.com/en-US/questions/804621