if you import the private keys it cannot do much (I don't know how it would even choose which to use as change address!)
In the version 4.1.3 and after that, if the "Use change address" option has been checked, electrum sends the change to one of unused imported addresses (if there's any, off course).
Prior to 4.1.3 update, the change was sent to the sending address even if the "Use change address" option had been checked.