You need to create a new style( preferred ) or modify the existing style.
Go to view styles
Dimension and the style currently in use
then "terminator and symbol" tab sheet
adjust "measure size"
This will change the dot size for all dots using that style. This can be a pain so I recommend creating a new style and setting the size dot you require. Then apply that style via the option on the command ribbon for only the dots/connectors you wish