If the font size on the computer suddenly becomes larger and you can't change the font size, you can try the following methods: Sometimes, when the operating system fails, the font size will suddenly change. Restarting the computer could solve these problems. 2 Check if there are any font drivers installed on the computer. These drivers may cause problems with the font size. Try uninstalling these drivers and then reinstalling the appropriate drivers. 3 Check if there are any third-party software installed on the computer. These software may cause problems with the font size. Try uninstalling the software and then reinstalling the appropriate software. 4 Try to use the font zooming function of the operating system. In the Windows operating system, you can adjust the window size or use the "font size" command to make the font smaller or larger. You can make the font smaller or larger in the Macs by adjusting the window size or using the "font size" command. If none of the above methods can solve the problem, it is recommended to back up important data and then re-install the operating system or contact the computer manufacturer for further help.