A family of Microsoft word processing software products for creating web, email, and print documents.
I don't think you can fix it, but it depends partly on how much smaller you made the pictures.
A screenshot is necessarily a bitmap with a certain number of pixels. When you reduce it, the software throws away some of the pixels. You don't notice the loss of information or sharpness because the remaining pixels are closer together. When you later enlarge the reduced picture, those pixels move apart again and the space between them has to be filled with something. But there's no way for the software to guess what colors those new pixels should be, other than "cloning" the ones it has. That's what causes the blurriness.
If you didn't reduce the sizes too much, it may help to copy the screenshots into a graphics editor such as IrfanView and use the Sharpen command. It won't be perfect, but it may be acceptable.