Set Default Customer Lookup to Contact
Many entities contains a Customer field (Lookup), and when you click on it a dialogbox appears. You can control the Look by (Søg efter) and View (Visning) to Contact (Kontaktperson) and for example My Active Contacts (Mine aktive kontaktpersoner).
// Set the defaulttype. 2 = Contact, 1 = Account etc.
document.getElementById("customerid").setAttribute("defaulttype", "2");
// Set the Default View (GUID of the desired View)
Xrm.Page.getControl("customerid").setDefaultView("A2D479C5-53E3-4C69-ADDD-802327E67A0D");