Hi @rnunley :
Do you mean that the time in Excel is different from time loading in PowerApps?
The reason why you met this problem is that:
- Excel save time as UTC time by default.
- PowerApps load time as local time by default.
So when PowerApps load time, it will transfer to local time zone automatically.
In order to solve the problems mentioned above, I suggest you save local time to Excel and load time in PowerApps as local time too. As @eka24 said,you can use the dateadd function.//make time zone the same.
I’v made a similar test for your reference:
I assume you are currently using a form, and the dropdown you mentioned is a datepicker control.
Step1:Set the Default of the Date DATA CARD (not the Default on the Date picker) to
DateAdd(ThisItem.Date,TimeZoneOffset(),Minutes)
Step2:Make sure the Date time zone properties of the date picker control is “Local”

Step3(If you want to update the date):Set the Update of the Date DATA CARD (not the Default Date on the Date picker) to
DateAdd(DateValue10.SelectedDate,-TimeZoneOffset(),Minutes)
The following is the schematic:

I think this link will help you a lot:
https://powerusers.microsoft.com/t5/Building-Power-Apps/Date-Picker-Sends-Wrong-Date/td-p/488289
Best Regards,
Bof