Safari keeps resetting my favourite tabs

I just bought a new MacBook air, and the safari on it has about 15 default tabs added into the "favourite" bookmark folder. If I delete some and quit Safari and open again, all deleted tabs will re-appear in the "favourite". Also if I add some webpages to "favourite" and then quit Safari, the tab will disappear. So basically I cannot change this "favourite" at all but keep all those recommended tabs (which I don't need any of them).

I've turned on Safari in iCloud in all devices, and on my iPad there's no such problem.