Yes I know and thanks for your return but actually, my screen 4K is broken so I'm using a old one which is full hd and the dif. is awesome, it looks tiny on my forum but not on Xenforo so I presume the issue is on my website but I don't know how do I have to change the font size...
I don't think zooming with the browser is the optimal solution cause when you visit a website and can't read a phrase or a word or anything else, you click on the cross and you visit another one. lol
It is the first time I see this, I always used a screen 4K and I absolutely want to change the font size even if I can increase the font size by 1px...