It sounds like your problem has more to do with retrieval. You _learn_ something when you retrieve something from your working memory or long-term memory (you build myelin, a fatty substance that isolates your synapses, which enables you to later retrieve the information).
The optimal way to learn is to use spaced repetition. It naturally happens if you apply the knowledge frequently, or you can use a flashcard app to track it.
If you struggle to _understand_ something, it often has to do with overwhelming your working memory. You are connecting several concepts that you don't understand. On average, most can keep seven items in their working memory, but after that, you'll start feeling lost.
When you internalize a few concepts by retrieving them, followed by a long break or sleep, you free your working memory to connect more concepts.