Changing your browser user agent can be a useful thing to do. I have found it to be a great way to 'emulate' / simulate your browser being a phone, tv or other device. There are multiple uses for this, but a good one is making YouTube think your browser is a TV to take advantage of YouTube TV options like using your phone as a remote control. Below I have listed how to do this in each browser listed.

Firefox

Note: This will last until reverted manually, which can be done by deleting the general.useragent.override preference (click the garbage can to the right of the preference).

1. In the search / url bar type about:config
2. Accept any popup about risks
3. In the search bar type general.useragent.override
4. If the preference exists skip to step 6 to change it
5. Select the String radio button and click +
6. Input the following options:
   • Name: general.useragent.override
   • Value: (see below for user agent list)
7. Click OK and start using your browser

Chrome

Note: This will last until reverted manually, which can be done by going through the below process again and checking Use browser default

1. Option the developer options by either:
   • Pressing F12
   • Clicking: 3 dots in the top right > more tools > developer tools
   • Keyboard shortcut: Ctrl + Shift + I
2. Click the Network tab in the top row options
3. Click the 3 dots in the top > more tools > Network Conditions
4. Beside the User agent section, Uncheck User browser default
5. In the drop-down select an option OR enter a custom user agent from the list provided in this article

User Agents

Best options (as of May 2023)

• MacOS
  • Mozilla/5.0 (Macintosh; Intel Mac OS X 13.2; rv:110.0) Gecko/20100101 Firefox/110.0
• iPhone
  • Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/110.0 Mobile/15E148 Safari/605.1.15
• Android
  • Mozilla/5.0 (Android 13; Mobile; rv:68.0) Gecko/68.0 Firefox/110.0
• TV (Samsung)
  • Mozilla/5.0 (SMART-TV; Linux; Tizen 2.4.0) AppleWebkit/538.1 (KHTML, like Gecko) SamsungBrowser/1.1 TV Safari/538.1

You can find more user agent options here or by searching "user agent list" online