Click on the Page Settings button in the right hand menu (column of icons running down the right side of the screen), as shown below.
Now choose the Font Face by clicking on the drop down under the label Font. Select the font you want to use from the available list of fonts
Next select the font size - this will be the default font size used in text content blocks for sales quotes.
FInally click on the Colour picker to set your default font colour for all text blocks in a sales quote.
After making your selections, click in the Save button.