Validate Tracking Code for Google Analytics

In Google Analytics, there are additional features to see richer reports like Demographics, etc. But Google wants the Analytics Tracking Code Script changed and updated. Here is what they ask, “Your Demographics and Interest Reports have been enabled, but your Analytics tracking code does not include the necessary support to show them. Learn more about the simple, one-line, one-time change to your tracking code to add this support.”

If you click Learn More, it goes to this page: https://support.google.com/analytics/answer/2444872/?hl=en&utm_id=ad&authuser=0

From what I gather, we are using the classic analytics code as opposed to the universal analytics.

Google wants us to replace this line:

ga.src = (‘https:’ == document.location.protocol ? ‘https://ssl’ : ‘http://www’) + ‘.google-analytics.com/ga.js’;

with this line:

ga.src = (‘https:’ == document.location.protocol ? ‘https://’ : ‘http://’) + ‘stats.g.doubleclick.net/dc.js’;

1. Can I make this change?
2. Where should/can I make this change?
3. Is it best to make this change in my child theme?

Thanks!

-Jeff