How did Hitler's attitude and faith towards and in his subordinates change and evolve between the pre-war and war years of World War II?
In general, Hitler was never a very trusting person and tended to use his subordinates in whatever ways seemed most useful to him. In other words, he was willing to be fairly cut-throat with his subordinates even in the years before the war. As the war turned bad, Hitler became much less trusting towards his subordinates.
An example of Hitler's ruthlessness can be seen in his actions towards Ernst Rohm. Rohm was an early ally of Hitler's in the Nazi Party and was the head of the SA under Hitler starting in 1931. However, once the Nazis came to power in Germany, Hitler decided that Rohm was a liability and a potential threat. He therefore had Rohm killed in 1934.
During the war, Hitler's main confidants were Hermann Goring, Joseph Goebbels and Heinrich Himmler. Goring was an example of how Hitler lost faith in some subordinates as the war went on. The Luftwaffe's inability to protect Germany helped to turn Hitler against Goring. Hitler eventually stopped meeting with Goring and Goring lost relevance in the Nazi Party.
Goebbels and Himmler maintained much of their power and of Hitler's trust throughout the war. As evidence of that, we know that Goebbels was with Hitler in his final days and that Hitler appointed Goebbels as his successor in his will. Himmler was similarly trusted by Hitler up until his attempts late in the war to negotiate with the Allies.
Overall, Hitler tended to turn against many of his subordinates even before the war. As the war went on, this tendency was magnified. However, he did continue to trust a few close confidants to the end.