Navigation Dropdown Not Working

Hi, 

I'm having an issue with my navigation bar. I just started using this platform yesterday, I'm inheriting someone else's work which makes things a little more difficult. I will try to keep this short and sweet.  

1) I'd like to add a navigation widget to one of my templates and have it look like this: 

2) For a reason I can't figure out, when I drag  the navigation widget onto my template with the Display set to 'Top Level Pages', Levels To Include set to 'All' and Template set to 'Pill', I get this:

3) When my theme is applied, I get this: 

4) In conclusion, why does one nav bar look like this:

and the other like this:

Both of them are in the header and both of them have the same settings:
Display: Top Level Pages
Levels to Include: All
Template: Pill

Extra:

My theme is not applied to the first navigation bar, only to the second. It seems pretty obvious that they both have different classes, but they don't. I still can't figure out why. When I create a New Template and dragged a navigation widget on the new template, it looks like this: 

not like this:

Again, this is my first day using this, I'm not a front-end developer and I'm inheriting someone else's work, a little help would be greatly appreciated. 

Thank you very much.