As the second one URL is easy to understand. Please let me know if it's going to affect my site SEO on changing the Youtube page.
In your case the new link will help to improve SEO.
Because it has the domain name so it will give priority in search.
By changing your current Youtube link in your site will not affect any other SEO because it's just an external link. The only thing you have to make sure you're changed URLs should be updated in all other places (wherever you're used older links).
When we talk about SEO, we definitely talk about Google :-). Since YouTube is part the the Google-family, this will definitely not bring negative effects. As I said earlier: you will have your domain-name and especially tablet in the new name; which is a good indicator for better SEO.
If you still have links online to the old channel, than change them to the new one.