To retain the settings for thumbnails or list etc., after you've made the change go to
Tools | Folder Options | View tab |
Click Apply to all Folders

For the size of Window Explorer you can try the following:
1. Open WE and manually drag it to the size you want.
The next time you open it should open to the new size

2. A more permanent solution is Right-click the WE Icon | Properties.
Change the Run from Normal window to Maximized | | Allpy | OK.

Now it will always open in the full window.