Click on the gear icon on the top right corner to go to Preferences. There, go to the Memory tab. In the Memory tab, you can choose to have 'Free Memory' data appear on your menubar. You can select the information to be displayed as a percentage or in a MegaByte number form. You can also toggle the app menubar icon to display or not along with the memory information on your menu bar. Furthermore, you can also select text size.