Remedial Help Needed

I hope I do not get laughed off the forum for such stupid questions….

#1
I am using the connections theme and I do not where to go to customize the links in the header.

#2
How can I change the number of recent comments and recent posts that are displayed in the sidebar?

#3
Why does embedding a utube video sometimes works perfectly and other times it send the blog all askew?

TYIA

Julie
[sig moderated]