you can change that via the forum ID

this forum has the ID 45

So the CSS code is

#wpforo #wpforo-wrap #wpf-forum-45 .wpforo-forum-title a{
color: #ff0000 !important;
}

Can somebody tell me how to change only one forum category, the 3rd, into the red color, i tried codes you post but all the time its apply on all categories

https://smartautomobili.com/

now working thank you

Yes it is, and this is the correct way if you want to change the colors of each forum individually. Don't forget to remove other CSS codes you've tried for this purpose.

Go to Dashboard > Forums > Dashboard and click the button.

Thank you for video guide

I have already corrected by removing additional #

anyway seems take time to update things over the dns or internet to get appear the result.

Let's see in few hr.

Thank you.

the mistake is still there

https://www.screencast.com/t/CIJKK8S4

Thank you for letting me my mistake. I have corrected by removing double #.

Still seems doesn't work any of css codes.

I have checked in different browser with private mode, if there is caching issue. No luck can you help/guide me to verify

Thank you for css code. Just one thing I want to clarify, 

what is the forum IDs, is it attached image number

remove the double # from your color code 😉 

then it works

#wpforo #wpforo-wrap .wpfl-1 .wpforo-forum-title a {
color: ##282828;
}