Assuming that you mean with "notes" unread threads...
Note there is a difference between Safari (as used on Mac's, iPhones and iPads) and other browsers. If you select
Show unread posts since last visit, then click on the first topic, read it, and then use
Back afterwards, the list will no longer have the item you just read on it. You can just click the next item.
On Firefox or Internet Explorer the list of items to be read remains intact, meaning
you have to (manually) keep track of which item still to read.
If that is the behaviour you are referring to your options are (in order of price): install Safari and use it on a PC; buy and use an iPad; buy and use a Mac. As an Apple shareholder, may I suggest you buy a Mac as you clearly already own an iPad.
Peter