If your volume is maxed on your pc and in YouTube, then you may need to get a pair of speakers. You can also try using one of the many add-ons.

but which add-on, can you give me a name? And how to get it.

Never used them before so you will have to figure it out.

https://addons.mozilla.org/en-US/firefox/search/?q=volume&platform=Linux&appver=86.0a1&utm_source=firefox-browser&utm_medium=firefox-browser&utm_content=addons-manager-search

Did you check the Windows volume mixer and the volume setting in the YouTube player ?

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" for websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data: "Manage Data"

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can remove all data stored in Firefox for a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data for that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Thank you so much for trying to help. the sound in you tube is at 100% and the sound on my computer is at 100%. I am too scared to death to attempt your solutions.

Don't you hear any sound on YouTube, or is this only low volume ?

I hear sound it's just low volume.

When you click on the speak in the system tray, what is the the volume at?

100 %

Do you have external speakers?

Not sure of your options in Win8, but can your right click on the speaker and then click on the sound mixer. Is there an option like App Volume and Device preference? see screenshot Post a screenshot.