Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

If there is still a problem, Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Did this help?

While you are in safe mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

ooooH finally! Thanks!

no no...i have another time the problem........ damn!

It came back?

https://support.mozilla.org/kb/Clear+Recent+History#w_how-do-i-remove-a-single-website-from-my-history

Remove History For One Site

Open the History Manager <Control><Shift> H. In the search bar, enter the name of the site. Right-click on one of the listings and select Forget About This Site. This should remove all information, including any passwords / settings.

Hello savio84,

An extension named 'YouTube High Definition' could be the culprit here .....

See :

https://old.reddit.com/r/firefox/comments/aesm24/youtube_redirecting_to_a_channel/

Would you please go to 3-bar menu => Add-ons => Extensions, and see if you can find that extension there (or any other extension that you didn't install yourself)  ?

If so : would you please remove it  ?

( Edit : typo .... )

i've only this in the picture

and this is the page of youtube:

savio84 said

i've only this in the picture

Well, your screenshot shows that you do have that extension installed that I mentioned : "YouTube High Definition" .....

Would you please remove it and see if that will solve the problem  ?

finally!!!!THANKS!

savio84 said

finally!!!!THANKS!

My pleasure  !

(things can be so simple, sometimes ..... )