Without taking a look at your specific situation, it’s very difficult to give a specific answer. There are simply too many different types of problems that involve paint not adhering to exterior surfaces. For example, there are terms such as alligatoring, blistering, checking and cracking to describe different problems that can occur. However, almost all paint failures are due to poor or improper surface preparation. Another cause is improper application. The use of quality paint also is important, but, as in your case, will not ensure against adhesion problems if the surface is not properly prepared and the paint is not applied correctly.
To briefly answer both your second and third questions, yes, you can correct your problem and by properly doing so avoid the same problem in the future. Remove all loose, flaking or peeling paint, clean, spot prime where necessary, solve any moisture problems you may have and repaint with a quality paint using correct application procedures.
That’s the brief answer. For a complete and authoritative answer to your specific paint problem, see your local independent paint retailer. In many cases they have a publication and/or CD-ROM disk entitledPaint Problem Solver which illustrates many common exterior and interior problems and explains the cause and solution.