Overriding the DateTime field in the Entity Form

Hi,

I have added logic to set datetime field on creation of task record in the Task entity.

if (formType == 1) {

 Xrm.Page.getAttribute("datetime").setValue(new Date());

}

But when I try to create it from UI and changed the Time  of the "datetime" field and tried to Save it.

It is not saving with the changed time. It is saving with current datetime only..