Newbie with a question on video output

[#1]

Community!  

I'm a complete novice, but I have one problem that is just vexing me like crazy!  When I build a timeline with all of my video, photos, sound tracks and everything else......I build it perfectly.  I size the videos and photos perfectly in the "Source Window" and I have the Display Monitor set to 100% so that nothing is distorted.   

BUT, When I got to export the video into Youtube format, the video size always gets totally messed up.  I don't know what I'm doing wrong.  Because when I am working in Premier Pro, I use the Effects control to scale it to fit the Display monitor perfectly.   Somehow, when I export media I can't figure out how to do it.  

Anyone have the same problem as a beginner? 

Thank you all!     The first screenshot shows my workspace and then the second video shows how small the video ends up when I export it.  That export media settings area kills me every time. 

[#2]

You want the Program Monitor set to 'Fit'. I know it seems a bit unintuitive and honestly I can't tell you what 100% zoom is meant to be a measure of. It will vary depending on the sequence size. In the 4k sequence I'm currently working in, for example, 100% is quite zoomed in (and it looks to be for you as well).

Edit to add some more info: What you do want to be 100, ideally, is the Scale of the video so that it fits your sequence. (Your video is scaled down to 42 to fit that 100% zoom level). It sounds like you are working with different types of media and presumably they will have some different frame sizes, so you'll either want to decide which of your pieces of source media is your "hero," the one that you will create your sequence frame size and frame rate based on, or you will want to decide what your intended output is meant to be (like 1920x1080 at 23.98 fps, for example).