It depends on how the website works internally. Nowadays, websites will often not use classical navigation (where the browsers loads a different page), but change content while staying on the same page. This means the back button won't work.

Hard to say without knowing on what website you're experiencing this though.

You definitely should not reinstall the browser though; the chance that this is due to a broken installation is less than 1%.

I think instead of pressing back arrow you should press the backspace key or you should re-install the browser.

on all web pages or only 1? try restarting the browser