cannot delete recent history as option not highlighted in TOOLS
I click on TOOLS and the option to 'clear recent history' is not live (light grey text). In other words clicking on it has no effect. This is also the same for 'stop private browsing'
All the other options under TOOLS are available (black text).
Alla svar (1)
You have Firefox set up so that it is always in private browsing mode or never remembering history.
To get out of that mode, in the Tools menu select Options. Go to the Privacy panel and if the setting at the top is set to "Never remember history", change it to one of the two other options. If you have it set to "Use custom settings for history", make sure the setting "Automatically start Firefox in a private browsing session" is not selected.