Disable Private Browsing

It's not permanent. Just close the window and private browsing will be gone.

Read this article for more info: https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history

Make sure that you do not run Firefox in permanent Private Browsing mode (Never remember history).

• Tools > Options > Privacy > Firefox will: "Use custom settings for history"
• Deselect: [ ] "Always use Private Browsing mode"

When you are in permanent PB mode then all windows are automatically in PB mode.