How to customize the interface language of the software?

I want to switch the software interface language from English to Spanish, how can I do thay?

When installing the Flip PDF or Flip PDF Professional, you should choose the default language for the main interface of the software as the first step, but the selected language can be modified if you need.

So, how to change the interface language?
1. Click “Options” on the frame of the software;
2. Press “Language” option, you will see the language list in the right side;
3. Just click a language from the language list and the software will pop up a tips to ask you to restart the software to change the language;

4. Restart the software, it will be in new picked language.