No one has a bad memory or good memory. It all depends on how we train our mind. We teach techniques which help a child to remember, retain and recall, short term memory, long term memory, photographic memory, Memory games, mental gymnast and so on.
Memory is related to your brain. It is one of the brain functions. Some people are good at memory and some people are not.
The problem is not with the memory. The problem is with the storage system, or the indexing system of the brain which we hardly ever train. Although the information is very much there, due to our negligence of not labeling it properly before storing, we are not able to recall.