The values plotted at the node and element centres are not plotted as real text but as poly lines. The default font-size for numbers is 0.18 cm. It can be changed using the menu Edit 
Options Plot option Size (plogeo.ini command HWER ).
In the presentation of quantitative data, stored in the background file in the unit m³/?/TU (TU = time unit of the model file), the conversion of data in different amounts and time units is offered.
By checking the box Plot values = 0 these values are explicitly shown, otherwise values equal zero are ignored.