Safari Volume slider. Click drops to zero and stays there. Won't change.

Thanks for replying, jfmusic0, and that additional info, it really helps! If this is only happening in Safari and on certain websites, as you mentioned that YouTube works as expected, we suggest following these steps:

"Check Safari extensions

If you installed any Safari extensions, turn extensions off. From the menu bar in Safari, choose Safari > Settings (or Preferences). Click Extensions, then deselect each extension to turn it off. Learn more about Safari extensions.

If you find that an extension is causing the issue, make sure that the extension is up to date.

Test with a private window 

A website can store cookies, caches, and other data on your Mac, and issues with that data can affect your use of the website. To prevent the website from using that data, view it in a private window: From the menu bar in Safari, choose File > New Private Window, or press Shift-Command-N.

If that works, use the following steps to remove the website's data, including its caches and cookies. The website can then create new data as needed. If it's a website that you sign in to, make sure that you know your sign-in information before continuing.

1. Choose Safari > Settings (or Preferences), then click Privacy.

2. Click Manage Website Data.

3. Select the affected website from the list shown.

4. Click Remove.

5. Click Done.

6. Open the website again in a non-private browser window.

Check Safari settings

The webpage might not be compatible with one or more browser settings, which you can turn on or off as needed. From the menu bar in Safari, choose Safari > Settings (or Preferences). Then click Websites, Privacy, or Security to access these settings:

* Privacy settings. These settings apply to all websites. For example, a website might require that you allow cross-site tracking, show your IP address, or allow cookies.

* Security settings. These settings apply to all websites. For example, a website might require that you enable JavaScript.

* Websites settings. These settings can be configured for specific websites. For example, a website might require that you allow pop-up windows, allow downloads, allow access to your camera or microphone, or turn off content blockers.

Check iCloud Private Relay

If you subscribe to iCloud+ and are using its Private Relay feature, try reloading the page without Private Relay: From the menu bar in Safari, choose View > Reload and Show IP Address. This menu item appears only when Private Relay is turned on for your network. Learn more about iCloud Private Relay.

Check VPN or other security software

If you installed VPN or other software that monitors or interacts with your network connections, that software could affect your use of the website or the internet. Learn about network issues related to VPN and other software. 

Check network settings

Certain network settings, such as custom proxy settings or custom DNS settings, can affect access to content on the internet. Even if you haven't changed these or other network settings yourself, you might have installed software that changed them for you. 

To find out whether the issue is with the network settings on your Mac, try viewing the page from a different web browser or different device on the same network. Or reset your network settings by setting up a new network location on your Mac.

If the issue affects other devices and web browsers on the same network, the issue is probably with the website, and you should contact the website developer for help. 

Learn more

* If the issue continues to affect only a particular webpage, contact the website developer for help."

And those steps are from here: If Safari doesn't open a page or work as expected on your Mac - Apple Support

Have a great day and thanks for using the Apple Support Communities!

Hi jfmusic0,

We appreciate you reaching out to us.

We’d like to gather additional details that may help us be in a better position to assist you.

Have you had the chance to restart your Mac? Shut down or restart your Mac - Apple Support

Are you experiencing the issue on multiple sites?

If you answer yes to both questions, please check if the issue persists while on safe mode. 

Safe mode does a basic check of your startup disk, similar to using First Aid in Disk Utility.

Performing this step may help resolve the issue, or further isolate the issue.

Below is an article to help guide you through the process.

How to use safe mode on your Mac

If the issue persists,  please test if the issue happens on a newly created user account. 

1. "On your Mac, choose Apple menu > System Settings, then click Users & Groups  in the sidebar. (You may need to scroll down.)
2. Click the Add Account button below the list of users on the right (you may be asked to enter your password.)
3. Click the New Account pop-up menu, then choose a type of user.
4. Enter a full name for the new user. An account name is generated automatically. To use a different account name, enter it now—you can’t change it later.
5. Enter a password for the user, then enter it again to verify. Enter a password hint to help the user remember their password.
6. Click Create User."

You can use the article below as a reference.

Add a user or group on Mac

Take care!