The battles were led by two different general because there are two different battles
The first battle of El Alamein was led by General Sir Claude Aukinlech. The Auk was a very prominent soldier and no-thrills lifestyle during campaign but he was bad at picking good company very much respected by his troops for his no-nonesese and when he took led in the field himself his plans were complicated and confusing and that’s the reason why people not understanding what they were supposed to do.
General Bernard Law Montgomery (later Field Marshal Sir Bernard Montgomery - 1st Viscount Montgomery of Alamein) led the 8th Army at the battle of Alam Halfa and the second battle of El Alamein. Simplicity was the key in orders, playing to the strengths of his own side was another and morale building and maintaining was essential. What annoyed people about Bernard Montgomery was he had a clarity of thought and uncompromising nature and, even more, his occasional tactlessness.