I have few websites, one of my websites got approved for Adsense so does it mean that I can start putting ads on all my websites or I have to get approval for all my websites?
The approval process has been changed.
Yes, you have to do.
Yes, you have to apply for all websites and Adsense will take some days to review that.
If everything will be good then your website will be approved. After this, You can put ads on your new website.