Best thing to do if you do not want your dialogs moving/disappearing
Alongside of your tabs dialog (on the far right) there is a small filled in arrow. right click on it and you will be given several options. In the menu that drops down click on
Lock tab to dockDo this with all the tabs you wish to keep open all the time.
Then once you have done this, go to edit - preferences, Under Interface you will find Window management. In this window, check on save window positions on exit and save window positions now.
Then after closing from each session and opening up again they will be in the same position unless you move them