Excel gridlines

I have been happily using Excel2007.  Now I am trying to move to Excel in Office 365 and Windows 11.  The gridlines are so faint as to be completely unreadable, thus making Excel unusable for me.  How can I make them darker and visible?

    Also, there must be a way to control which cell becomes active when enter is struck.  I want no movement until I use the arrow keys--the way I have it in Excel 2007.