If you are using a PC, press CTRL + SHIFT + DELETE and select "Clear browsing data", "Clear now", "Clear" or "Delete".
If you are using Chrome, you need to select the 'Advanced' option in order to clear your cache fully:
Now, select the 'All time' time range and tick ALL of the boxes (you will need to scroll down):
Different browsers (eg Firefox) may have different options, but in all cases, we advise clearing ALL data categories for the longest time frame available.
If you are using Safari on a Mac, select History -> Clear History and select the ALL timeframe.
If you are using Firefox on a Mac, select History -> Clear Recent History.