You can add fonts to a style when creating your documents, if the font required is not available check out the article: Adding a font to a template
To change the font on an element:
Navigate to the template.
Then, click on the element.
In the properties window, you can see the current style the element.
On the Properties tab in the Text section, you can change the font by using the dropdown.
Select the required font.
Editing a style will apply this change to all elements using this style.
If the element is using a style.
Click on the Style Designer.
Choose the Style you want to change.
Head to the Appearance section and change the font.
Click OK when you are happy with the changes.
The change has now been saved to the Style.
Save the template.
Learn more about Template Styles in documents here: How to save and apply a Style to templates