Change header settings

[elenaalendeberya]

Hi. I need to help with header settings.
1. I want to fix it on scroll. I Add this code.
header.mooc.fix {
position:fixed !important;
}
But at the same time, the title of the page disappeared. How can it be changed?

2. What does this sign mean?(1)
What does “0” mean in the header(2)

[elenaalendeberya]

Hi. How can I do this?