Firefox 52.0 was released earlier this week with some noticeable changes. This new version increases awareness of insecure sites by showing a warning message where there are username and password fields.
One other big change is the removal of NPAPI-based plugins with the exception being Adobe Flash. So if you need sites that use Java and Silverlight, you will need to use a different browser or stick to an older version of Firefox.
To update, try the following steps:
Windows: Go to the Help menu and select About.
Mac: Go to the Firefox menu and select About Firefox.
To download a fresh copy of Firefox on either Windows or Mac, you can go to the link below and click the green Download Firefox button:
Link –> Mozilla Firefox
SOURCE: Mozilla