Is the Kindle connected to Wi-Fi?
The Automatic Time Zone option requires Wi-Fi but the manual option does not. Are you using the Automatic Time Zone option?
Go into the Date and Time then turn off Automatic Time Zone and adjust it manually. Does it work now?
Sorry, the text block was jammed together so it was difficult to read.
First, go to the SETTINGS menu which you access thru pulling down top screen, hit more and go to MY ACCOUNT.
Click on EMAIL, CONTACTS, CALENDARS. Click on CALENDAR GENERAL SETTINGS. Make sure the USE DEFAULT TIME ZONE is ON. Then click on SET DEFAULT TIME ZONE.
Pick whichever time zone you are in then hit back arrow back to your SETTINGS menu.
Go to LOCATION BASED SERVICES and turn that on. Then hit back arrow to take you back to SETTINGS SCREEN. Then go to DEVICE. Go to DATE AND TIME. Go to SELECT TIME ZONE and go from there.
Does that work?
Unfortunately, I do not know what you have or have not already tried unless they are listed in the question.
Did you try these?
Did the steps above work for you?