Change display form fields order programmatically
If we want to change fields order in new form, edit form and display form without editing aspx in Sharepoint designer, we can change it in content type through UI or programmatically.
In following example, we change order of Event content type
Add-PSSnapin microsoft.sharepoint.powershell -ea 0
$webUrl = "https://yoursitecollectionurl"
$ctName = "Event"
#note: StartDate, EndDate are fields Start Time(EventDate), End Time (EndTime) in FieldLinks references
$fieldsOrder = ("StartDate", "EndDate", "Location", "Title")
$web = Get-SPWeb $webUrl
$contentType = $web.ContentTypes[$ctName]
#see original order
$contentType.FieldLinks ' select DisplayName
$contentType.FieldLinks.Reorder($fieldsOrder);
$contentType.Update($true);
"============================="
#see modified order
$contentType.FieldLinks ' select DisplayName