mileage I have recently bought 4 cars with low mileage ex.106k 110k 120 and one unknown

all these autos within 15 months the engines blew..yes! transmission,heads,2 overheated and could pull over fast enough.replace radiater and ect. All these cars were serviced by myself(cost) there were questions by these mechanics but really unsure..WEll,there questions were answer. O.K . Now my question?---I again need a low cost car and on the internet I find cars with these low miles.Can these cars speedometer be rollback? It seems to me with my last 4 autos ,I bought from ,,tw0 with dealers and 2 with owners.. I know what they say,but please tell me straight,I cannot make these mistakes again..I have but just a little that I can save..and can you tell me how to check this problem?? please take time to answer my questions..I"M so anxious about this.
thank you,
ms.dene walt