I don't think the software allows you to change the charset. I've managed to install a demo version, but there was nothing related to charset (customization, change, encoding, etc). If you already have the software, then you can use it the way it is right now. However, there is the possibility to change the charset from the HTML file.
Generate your gallery and then open the main HTML file in a text editor and add the charset as described on W3School: http://www.w3schools.com/html/html_charset.asp
