How to Block 'Pop-up Windows' in Firefox Browser on Windows 10?
Step 1: Open 'Firefox' Browser, and then click on 'Menu' icon at the top right.
Step 2: Click on 'Options', and then click on 'Privacy & Security' in left menu.
Step 3: Scroll down to 'Permissions' section, and then check the box beside 'Block pop-up windows.'
Step 4: Also, if you want to allow some websites that can have pop-up windows, click on 'Exceptions...' button next to 'Block pop-up windows.'
Step 5: Now, in new window, you can add the website under 'Address of website.' After that, click on 'Allow' button. After you done, click on 'Save Changes' button.