how to change title on default sidebar, show the entire post

hi, guys
im trying to show the entire post on my blog but still no success.
im using the child theme of highend.
I have also tried to edit the color of the second top bar but i see no changes. i don’t know how this part is called on the customizer.
and i also would like to change the title of the default sidebar.
what would be the code to add to the child theme then?
many thanks in advance!!