(1) when the county designated in the complaint is not the proper county;
(2) when there is reason to believe that an impartial trial cannot be had in the county, city, or precinct designated in the complaint;
(3) when the convenience of witnesses and the ends of justice would be promoted by the change;
(4) when all the parties to an action, by stipulation or by consent in open court entered in the minutes, agree that the place of trial may be changed to another county.