The setting should be all you need, assuming you are closing the old window before opening the new one. (It saves the last window you closed, and will re-open a similar window the next time you open one.)
If you want something else, how are you defining "last folder"? That could mean a lot of different things, like the last path in a folder tab you activated, not just the last folder opened or closed in a new window.
The Last Folder is one of the following possibilities:
The folder shown in the lister tree that has the file/folder name, size, type, modified, attr columns, etc.
I have tried completely closing and restarting Dopus, but it aways opens the same folder.
If I click the toolbar button with the Go New, i simply want to duplicate the lister I am looking at, including the current showing folder(s).
It appears the lister is remembering my Tab setting but only the directory portion and not the folder path portion of the tab. I think I need to Unlock the folder tab so the lister returns to the last opened folder.