I have this application and the labels are hard to see on my phone.
It is not readily apparent how to increase the font size and/or change it to bold type.
For the x-axis, you can change the font size and color under props.timeAxis.tick.label.font.size and .color
For the y-axis, you'll need to add an axis and a trend as described in this post, then adjust the font size and color under props.plots[0].axes[0].tick.label.font.size and .color