What browser are you using? I used to use Internet Explorer, but recently have found that Google Chrome works a lot better for me. Except I have to switch back to IE when using PayPal to print postage.
Anyway, whatever browser you have is going to have a "tools" option for the internet. On Google Chrome, you click on the horizontal lines icon in the upper righthand corner, then click on "tools", then click on "browsing data" to get to where you can clear cache and delete cookies. I would have to start up IE to give you explicit directions for that one, but it's easy there too.
There are other browsers I haven't used, such as Firefox. Do you know what browser you are using?