Not able to change font color in some cells of Microsoft Excel

I can not change the font color in certain cells. When I type in the cell I see the color I want until I hit enter. Then it turns back to black. Help.

Any conditional formatting attached to those "certain cells. Then try Format > Conditional Formatting. How about background color? Does that show up. If it were "all cells" I would suggest this KB Article. The fill color, the fill pattern, or the line color of a WordArt or AutoShape object in an Office document does not change As directed, change the High Contrast setting in Windows OS

It can also be due to protection in the file because of which you are facing the issue. I will recommend you to first unlock the sheet entirely and then try to modify your font colors.