Gold Changing top menu font size and background colour

Can you submit your web url please ?

Here are the default settings, make sure you use a custom css plugin or a child theme.
Background color

.navbar-inverse {
background-color: #10B9B9;
border-color: #10B9B9 !important;
}

Font color

.navbar-nav>li>a {
color: #fff !important;
}

Amazing, thank you batharoy. I shall give that a whirl shortly,

So, being rather naive, I have just looked up what a child theme is. I understand the CSS plugin. I am not freaking out as it says that rather than edit the main theme files (which is what I have spent my entire week doing!) I should use a child theme. Is this correct? I have been making changes to the main php files of the theme to get my desired result – have a horrible feeling I am ballsing this up!

Thanks

You definitely should be using a child theme for editing PHP files otherwise all the changes you have made will be overwritten if you update the theme. CSS only edits can get away with a plugin but IMO you should use a child for any customization.
EDIT: At least your learning this before you update the theme ??

Thank you for your advice – and yes, pleased I have learnt this early on in my HTML learning curve!!! Whilst I have you (and thank you for your time so far!!) can I simply paste all the edits that I have made already into the CSS plugin or child theme? Will that work in exactly the same way?

All CSS files are read from top to bottom. The plug in will take care of where to put the styling.
With a child theme, one of the first lines is a call to the parent CSS file so anything you put in there (below @import url) will be read after the parent css and be applied.

Note: Anywhere the word “!important” is used in the parent must also be used in the child for that element to be affected.

Thank you so much. Have sorted this all now and have my child theme and CSS editor all up and running. Shall start again. You have saved me a whole heap of time, thanks.