Errors can occur in Excel due to users typing the wrong formula references, accidentally deleting an important cell or row in the spreadsheet, and more.

To change Gridline color in Excel, use Excel Options, apply a custom-colored border to the cells, or apply a custom line color. Full details here.

The default active cell format in Microsoft Excel isn't all that easy to see, but you can use this easy-to-implement code solution to change that.