The first screen which will display after TurboCASH4 is launched for the first time, is the "Choose a language" screen. 
TurboCASH4 - Choose language

Select your Language and click on OK the button.

Some languages may not display correctly if your system locale in the Regional and Language Settings option in the Control Panel of your system does not support the language and system locale (unicode).

English is the default (driver language file – used as the basis for translation, and to customise language files). For example, the en-American and the en-UK files contain specific label, text, currency and tax terminology for each country.

Should you select the incorrect language at this stage, you may change the language in the File → Switch language menu.