To change size of all items, text size of title bars, menus, message boxes, palette titles, icons, and tooltips on desktop in Windows 8, follow these steps:
1) If you want to change the text fonts to smaller or bigger, click on “Make texts and other items larger or smaller”.
2) Then, on the “Change the size of all items” page, select “Smaller”, “Medium” or “Larger”.
3) If you wish to change the size to any other settings as per your choice then click on “Custom sizing options”. In the “Custom sizing options” dialog box, select a percentage from the drop down menu or drag the ruler. If you want to use the Windows XP style scaling then select the option “Use Windows XP style scaling”. When you are done, click on “OK”.
4) You can change only the text size of specific items on the desktop and let other things as they were. Select an item like “Title bars”, “Menus”, “Message boxes”, “Palette titles”, “Icons”, “Tooltips”. Select the font size for the specific item.
5) Check the option “Bold” to make the text of specific item to “Bold”.
6) When you are done, click on “Apply”.