please, follow this tutorial in order to change the display font settings in RexHMI designer:

1. Open .svg file with the display you want to change the font at.

2. Select the diplay and press CTRL + SHIFT + X (Editor XML). You should see something like this:
   

3. Under Display group select "<svg:text..." part (as highlighted in following picture) and press CTRL + SHIFT + T (Text and fonts)
   

4. Change the font.

Note: Please, remember that the chosen font must be installed on the computer where you would like to see the visualisation (typically your host computer).

I hope the above is useful to you.

Cheers, Tomas

Do I need to add in the .js file something like :

display.style.font = "arial";