Admin Dashboard doesn't remember layout

I have the same Problem like it is described here:
https://core.trac.ww.wp.xz.cn/ticket/13424

On my Admin Dashboard I have permanently the default sort of the boxes. (like it is described on the linked site)

I try to drag’n’drop my boxes as I want, fiddle around some, hit refresh and they show up back like they did in the begining.

I tryed to find the mentioned table to delete it like they suggested it, but i can’t find it.

I deleted my site and browsercash, I deactivated my plugins, I reinstalled the WordPress Version. I don’t know what I should do now…

Thank you for your help!!!