@YouTube Hello, how are you? I wanted to ask for your help, my channel is no longer being monetized, it has this option disabled. I do not know why, in the past I lost my channel, I did not know how the rules of YouTube worked, it was the beginning of my work with YouTube.
As per the new eligibility requirements, a channel would need 4k watch hours (240,000 mins) and 1k subscribers in the past 12 months to be monetized. Once you meet the threshold, the channel will be reviewed for YPP. More info here: https://goo.gl/5joiih . Hope this helps.