blog header sizing and showing questions

Hi team,
thank you for your help in advance!
I have a couple of questions as below:

  1. when I choose a featured picture for a single blog, it shows nicely on the page of archive page(pic:question1-1), however, when I click into the single blog, the header showing for mobile page is too large(pic: question1-2), I have to scroll down too long to see the actual contain of the blog. Is there a way to resize the blog header to shorter(less height), or not even showing the featured pic as the blog header(if I don’t have a featured pic, the header will show a big long white area)?
  2. I have chosen the featured pic for each blog, but my front page showing is as pic:question2-1, not showing each featured pic?
    our website blog address is: 植髮案例 與文章分享-院長林俊志醫師本人實際經手案例-秀冠植髮診所