How to set Safari as your default browser
Setting Safari as your default web browser in OS X is very easy. Here's a guide showing you how to do it.
The setting for controlling your default browser in OS X is actually controlled from within Apple's own web browser itself.
Click the "Safari" menu item and choose "Preferences"
Safari's Preferences will let you change many things about Safari, including your default browser.
Choose the browser you want to be the default
Safari's Preferences will open on the General tab. The top item you see on the General tab is a select field labelled Default web browser:
You will see which ever browser you currently have set as your default there. This is a "select" field - you can click it and another menu will appear giving you various options to select.
When you click it, you will see a list of all the web browsers that are installed on your computer. Pick the one that you want to be your default browser for this computer.
Close the Preferences window
Now that you have selected your default browser for macOS, you can close the Preferences window (by clicking the red dot in the top-left corner) and resume your web browsing.