Unless you manually installed the Firefox APK on your device (which is unlikely), you probably installed it through the Google Play Store, which is the official app store for Android devices. Although updates are usually handled automatically through the Google Play Store, you can also check if there are updates available. To do that, open the Google Play app on your device. Press the menu button (the three lines) in the top-left of the screen and select '''My apps & games'''. Google Play will look at all of your apps on your device and show you what updates are ready but not installed yet. Those will be listed in the '''Pending Updates''' section. Any updates that have already been installed recently will be in the '''Recently Updated''' section. If Firefox is not listed under the '''Update Pending''' section, it's up to date. If Firefox is listed under the '''Update Pending''' section and you want to update it right away (rather than waiting for Google Play to do it on it's schedule, you can press the '''Update''' button next to Firefox or press the '''Update All''' button to update every app on your device. Alternatively, if you look up Firefox on the Google Play store, you can find the listing for the app. If the green button on the listing says '''Update''', then Firefox has an update available to install. If the green button says '''Open''', then Firefox is up to date. Additionally, you could compare the version number included on the Firefox listing on Google Play in the '''About this app''' section with the version number found in the Firefox app under the '''Settings''' > '''About Firefox''' page. Hope this answers your question.