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.

Open an Excel spreadsheet Select the cell or cells Click on the Borders button Select an option from the Border menu Change the color. To begin, open the Excel spreadsheet. The next step is to ...

The default border color in Excel is black, but you can change this to another color, such as orange or red.

If you'd like to change your legend's border color to make it more noticeable, click the Format Legend's "Border" button and then click "Color" to display a list of colors.

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.