Change mouse over text color?

The text on my main navigation menu changes to white on mouse over. I would like to change that to black, but can’t find the offending element. Can someone assist, and more importantly, tell me exactly how you arrived at the solution, so I can do this myself in the future.

I have done an inspect element on the offending element, but there is nothing obvious to me. I can’t prove it, but it seems to me that carrying out an inspect element on the same element will produce inconsistent output. Does this occur in reality, or am I making that up?

My site is: https://www.teflworld-koh-samui.com/test/