How do I customise Screen zoom and Font size on my Samsung phone?

The Screen zoom and font settings allows you to adjust the visual settings of the zooming sensitivity and the font size.

If you are unable to select Font size and screen zoom,  there could be a possibility that a theme or third party application could be the cause of this. If that is the case, you may need to reset your system settings or uninstall the conflicting application.

To reset your system settings head into your Settings > General Management > Reset > Reset Settings.
Please keep in mind that resetting your settings will remove any customisations set on your Galaxy device, your phone will be reset to its default settings excluding your security, language and account settings.