Youtube channel monetization

Here is my issue. My channel has completed necessary watch hours and subscribers. Till now I have applied 5 times for monetization, but it's been rejected by saying that my channel has '' Used content '' . Although I have deleted more than half videos in my channel and now except 4 slide show videos, whatever videos i have , they have my voiceover and my own editing. But still I don't know why it's getting rejected with same '' used content '' issue. It's been happening since last year's September.

So now I want someone who can go through my channel, check every video and tell me what's possibly wrong with my channel and why it's getting rejected.

My channel link is : https://www.youtube.com/channel/UCN2FsFlUagCgyIp90FLft4A

Thanks.