In addition to praying for assistance in learning, I would suggest that perhaps you can try different techniques for learning. For instance, some people memorize well if they memorize to a fixed set of sounds (such as copying someone's recitation from a recording and always reciting it the same way until it is fully memorized). Others memorize well if they visualize the contents of the text well. Some people even use hand gestures with meanings to help with memorizing.
Personally, I find that knowing more about the tafsir of ayat helps me to remember them better, since I am able to put them in place better and understand how they relate to each other.
I heard of someone once who memorized the whole Qur'an during advertisements on TV. He used to sit and watch the news and then, every day during the advertisements, memorize an ayah or two. So sometimes having small habits during the day to practice can also be helpful, in addition to longer sessions.
I also find that if I wish to remember something, repeating it while I am doing something else (walking, cooking, etc) helps me to review it in such a way that it is remembered better, because it needs to come out while I am distracted and not focusing on it. Inshallah this is not disrespectful to the Qur'an, but just suggesting it as a possibility.
I am sure there are also other techniques.
I am sure you will get more suggestions from others, but I just thought I would share those.
Also to repeat what you already know daily or as often as possible helps.
Sometimes the challenge with remembering is just due to age, since children are blessed to remember almost everything they see and hear, alas, this capacity sometimes wanes with age while at the same time we grow more busy and our minds full of many other things. So this is another reason to try new techniques. Inshallah Allah will help.