If you are whacked out seeing the time difference in your system when you switch between your operating systems especially between Windows 7 and Ubuntu 16.04, the you are not the only one. I have faced the similar issue and I will share the solution which worked out for me. Feel free to try it out or you can revert the changes.

This issue occurs because Ubuntu stores time on the hardware clock as UTC by default but Microsoft stores it as local time.

What we will try is to make Ubuntu store time on hardware clock as local time.Log in to Ubuntu and run the following command :-timedatectl set-local-rtc 1.To check if Ubuntu uses localtime run the following command:-timedatectl.It should display "RTC in local TZ: yes". Now try switching your Operating Systems and see if the issue has been solved.

If the issue is not solved you can revert changes by running the following command :-timedatectl set-local-rtc 0.