During writing the code, while I am in the middle part of the notebook I always want to include some import statements but for that I always have to scroll up to the top cell write the import statement and scroll back down to the previous working cell and continue from there. Is there a keyboard shortcut for this?
Are you sure you are using the classic notebook interface as your topic tags indicate?
JupyterLab lets you open two views of the notebook side-by-side (or even above and below if you prefer) so that you can edit different parts in the two views. See here as detailed under '‘Create multiple synchronized views of a single notebook’ in JupyterLab’s Notebooks documentation.
It’s abilities like these that make JupyterLab the current generation interface.