On Mozilla Firefox, it is very easy to find and download updates.
Steps
Part 1 of 2: Update Firefox manually

Step 1. Open the Firefox app
It is a round icon that represents a terrestrial globe surrounded by a fox.

Step 2. Click ☰
Select the Help option from the drop-down menu.

Step 3. Choose the About Firefox option
Firefox will open a dialog box, then check if new updates are available and download them automatically.
Note:
this will not work on Linux if you installed Firefox using a package manager like APT or YUM. In this case, you need to update Firefox through your package manager.

Step 4. Select Restart Firefox to update
Updates will be installed when Firefox restarts.
Part 2 of 2: Configure Automatic Updates

Step 1. Open the Firefox app
It is a round icon that represents a terrestrial globe surrounded by a fox.

Step 2. Click ☰ at the top left of the screen

Step 3. Choose Options

Step 4. Select Advanced
This option is at the bottom of the menu, on the left side of the window.

Step 5. Click Update
It's a tab at the very top of the window.

Step 6. Select a setting in Firefox Updates
Check one of the following boxes:
- automatically install updates (recommended for your safety);
- check for updates, but let me decide whether to install them;
- never check for updates (not recommended, this represents a security risk).

Step 7. Close the tab by clicking on the "x" next to the Options tab
Your update settings are now configured.