If you have more than one app that can be used for same action, You may select any app you want to use on Kindle Fire HD. You can change or clear the default app at anytime.
Amazon Kindle Fire HD has Silk as default browser. If you installed another browser like Maxthon on Kindle Fire HD, It will ask you to select default app for launching Web app or links.
You may want to change the default app for browser after setting it to Silk or Maxthon etc.
How to change default app for launching on Kindle Fire HD
1. Go to Kindle Fire Home Screen > More Settings > Applications > Installed Applications > Filter by All Applications
2. Tap on the app you want to clear the default settings for. Suppose, If you set Silk as default browser, Tap on Silk to application details.
3. Scroll down to see “Launch by default” section. Tap on “Clear Defaults” to clear this app.
4. On your Kindle Fire, Go to Home Screen > Tap on Web > Go to any web site > Click on a link > It will ask again to select the app for completing action. You can select any browser you want to use by default. Of course, You need to have more than one browser installed to get the prompt.