Safari resets when quit or Mac restarted

Ever since I purchased my new MacBook Air earlier in the year, Safari closes all tabs and resets itself every time I quit the app or restart my MacBook.

All my tabs close, but pinned tabs stay and reset themselves to the page they were on the first day I got my Mac. For example, my Amazon pinned tab reverts itself to a search that I performed on the first day I got my Mac, before Safari was quit for the first time.

This is especially annoying behaviour, so hopeful someone has come across this as it has not happened to me on previous MacBook's.

I'm on 10.13.1 now and the problem persists.