I have installed sage-7.4.ova for Windows 10, 64-bit and the Windows Virtual Box. But the window that comes up after the run of sage-7.4 is quite different from the one shown in the step 3.3 of the instructions (which I followed to the letter): it does have File, Machine and other options in the upper Menu Bar, but the rest is completely different: there is a 'jupyter' sub-window with the run-down list of files, such as 'sage', sage-7.4', 'notebook-browser', etc. with the upload and new buttons in the upper-right corner of the sub-window, no command line and pressing Right-Ctrl + F1 does not bring anything (nothing changes.) Any suggestions?