Noah, I wanted to thank you for taking the time to do this for me.
I have figured out my problem (in case anyone new to web design/webflow comes across this in the future).
What it was (for me at least) was that I didn’t realise the following:
If when aligning the children of a section it doesn’t move left or right (justify) it’s probably because you’ve used a Webflow container which is of course forced in the centre so it won’t move.
If there’s no container and when aligning the children of a section it doesn’t move up or down or left or right it means there’s an overriding up or down / left or right alignment on a child element within that section.
I THINK this is where I was going wrong and clicking align or justify was just doing nothing to the children elements within the section (Nav Bar).
Thank you again Noah anyway!