It depends on how the page is coded. If the site has set the links to open in a new window, Firefox normally opens them in a new tab instead. But if the links are set to open in the same tab, Firefox doesn't change that to open them in a new tab.

Search sites usually have an option in their settings/preferences to choose between the same tab and a new window/tab. For example, with Google: https://www.google.com/preferences

For other sites, you might need to use an add-on. As an example: https://addons.mozilla.org/firefox/addon/open-link-with-new-tab/ (you need to go into its options to choose your preferred behavior)

Any progress so far?

although you are very kind in attempting to help, your answer does not satisfy. i had no problem with Firefox/ Mozilla opening in new tab when i clicked on the link, it only started today. i have tried several different links and still had the issue. i re-checked my settings and found that they are as before (open in new tab) but it still makes me right-click to open in new tab. thank you so much for trying to help. i really appreciate it.

Is the problem on a specific page or site? Such as a search results page?

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

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

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

The default option is to open links in a new tab. You could check the preference in about:config. The value should be 3. An extension may have changed it. browser.link.open_newwindow

https://support.mozilla.org/en-US/kb/about-config-editor-firefox

it was actually a combination of suggestions that solved the problem. thank you all so much for your help!!