Zoho Creator updates each record submission with the name of the login user who added the record and the time when it was added. The following code added to the on edit -> validate block of the Script tab will be executed when a record is edited. If the added user name is not the same as the login username, the record is not allowed for editing.
if (input.Added_User != zoho.loginuser)
{
alert "You can modify only your records";
cancel submit;
}