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.

How to Make Colors Change With Validation in Excel. Excel's conditional formatting tool applies formatting depending on cells' contents. Validation rules can change cells font, style, size or border.

How to Change Grid Line Colors on a Chart With Microsoft Excel. Grid lines add horizontal and/or vertical lines to your graph that aid in measuring graph values.

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.