Try the Materials Informatics Toolkit, which is designed to easily handle SMILES data. This and other helpful add-ins are available in the JMP® Marketplace
Another quick (and dirty trick) is to hold "CTRL" + "SHIFT" + "+" to increase the overall font size across all elements (table, plots...) in JMP To reduce font size, hold "CTRL" + "SHIFT" + "-"
The method that @Thierry_S suggests is great when you are doing a presentation. One thing I've never known - is there a way to reset the size (without counting the number of times you've clicked the plus sign?). Something like CTRL+Shift+0 ?