There s finer control possible via prefs on the about:config page.

For Normal Links like you probably already have:

• browser.link.open_newwindow = 3
  1:current tab; 2:new window; 3:new tab;

You can possibly always divert JavaScript Links:

• browser.link.open_newwindow.restriction = 0
  0:divert always;1:divert never;2:divert no features

You can open the about:config page via the location/address bar. You can click the button to "Accept the Risk and Continue".

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

Note: I have come across links that somehow open new windows regardless of settings. And many links to Microsoft open in Edge or Internet Explorer.