Hi @AmrKadry93,

I am quite sure this is not possible to do in Canvas itself.  If you export the gradebook to a CSV, you could open the CSV in Excel and transpose the rows and columns to get what I believe you want.  If you want to import data back into Canvas, you'd have to transpose the data back again first so that assignments were in columns and students were in the rows, otherwise the import would fail or do something very unpredictable and undesirable.

Hope this helps!

-Chris