"過去の思い出は必ずしも当時のことを思い出すことではない"

Simplified Meaning:

When we think back on our memories, they might not always be accurate reflections of what actually happened. Our recollections can be influenced by our feelings, wishes, or even by other people's stories. For example, imagine you had a childhood friend, and you remember them as always being kind and fun. However, if you met them again years later, you might find out they were not always that nice. Our brains sometimes change the details of our memories without us realizing it. This is like when people look at old photos and recall the past with a sense of nostalgia, forgetting any bad times they might have had. It’s important to remind ourselves that our memories are not always perfect. To apply this to real life, whenever you're looking back at your past, try to remember the good and the bad equally. If you're making decisions based on your memories, it might help to check the facts or talk to others who were there. This way, you can make sure you're not letting false memories guide you.