i have problemes of concentration and understanding

i am writing this because i need help, i have problems of concentration and understanding (it depends on the situation) but for example i read a book about the greek mythology, and i spend 1:30h to 2h juste to read only 10 /15 pages, and there is some part that i can't understand them even when i take my time (i used chat gpt to understand it), and now i am reading a book about video games , and i am only at the introduction but i feel that i am not understanding anything, even when i take my time to read sentence by sentence. And it's the same thing when i see some youtube video, like an interview or something that i want to learn, some times i can't stay focus for only 10 seconds, and i stay rplaying moments of a video even 5 times
and knowing that i understand simples thing like when i talk with chat gpt
but when it's a bit complex i have this problems
so please, if anyone can help me, don't hesitate to write me answers