Steps to  make Firefox or Chrome the default browser in Windows:

• Select the Settings icon from the Windows Start menu.
• On the left pane, click Apps, then Default Apps.
• Scroll down and select Web browser from the drop-down menu.
• In the pop-up window that appears with a list of available browsers, select Firefox.
• Firefox is now your default web browser. To save your changes, close the Settings window.
• Click the Start button on your computer.
• Select Settings from the drop-down menu.
• Go to Apps and select it. Apps that are installed by default.
• Go to Google Chrome and open it.
• Click the current setting for each file type or link type you want to alter.
• Go to Google Chrome and open it.

Read More : How can I switch to Firefox from Chrome?