Most links are greyed out (Linux)

[pwabrahams]

Something has changed, but I don't know what, and now almost all links in my web pages are greyed out. I also note that when I open a new tab with +, it creates a new private window whether or not I want that window to be private. I may have changed something unintentionally, but I don't know what. Why are these things happening?

[Brummelchen]

common solutions for most problems.
https://support.mozilla.org/en-US/kb/tr ... x-problems

test firefox in safe-mode please:
https://support.mozilla.org/en-US/kb/tr ... -safe-mode
or
http://kb.mozillazine.org/Safe_mode

[jscher2000]

Does your Firefox remember history as you browse?

[dickvl]

Sounds that you run Firefox in permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History).
Preferences -> Privacy & Security -> Firefox will: "Use custom settings for history":
"Always use Private Browsing mode"

Quote:
when I open a new tab with +, it creates a new private window

You appear to be using Firefox from the Ubuntu repositories, so maybe try the version from the Mozilla server.
https://www.mozilla.org/en-US/firefox/all/