Date time is not proper

Hello All,

I'm taking datetime values from the user in the below order

2018-01-12T11:11:11 i.e YYYY-MM-DDTHH:MM:SS

Now I'm converting this enter date into proper format using userdatetime() function based on the users profile timezone. Suppose my timezone is EDT, So it will convert the above date in the below format

1/12/2018 11:11 AM EDT. Now there is an option to edit this date through datetime picker control. When user selects that option at that time instead of displaying this particular date, Its getting converted into 01/12/2018 7:11 AM. I.e 4 hours less than what is being added. Can someone please help me to sort out this issue and let me know how can I display the exact date without any conversion? Thanks in advance