Format the Countdown / Countdown Design

Hi, I am Daniel and I hope anybody can help me.

We work with Version 2.0.3 / WP 4.01.

The current display-format is
49 : 18 : 55 : 28

How can I change the format to:
49 Days : 18 Hours : 55 Minutes : 28 seconds

I would be glad to get a hint which files are involved.

Best regards, Daniel

https://ww.wp.xz.cn/plugins/wp-maintenance-mode/