Glenwf,
Ticks are mainly used in architectural drawings arrows are used in mechanical drafting.
Here are my settings that seem to work ok, under Edit>Current Drawing Preferences>Dimensions
General Factor - 1
General Scale - 1
Text Height - 25
Extension line extension - 10
Extension line offset - 10
Dimension line gap - 5
Arrow Size - 5 (This is the one you are looking for increase size to see better)
Tick Size - 5
A helpful hint: Create a new drawing set all the setting of the current drawing and then save it in your temple folder, change app preferences to use that drawing as your starting drawing when selecting a new drawing, this way you do not have to set up each drawing with your preferred settings.
When you have the will to always learn there is nothing that is impossible....The day you stop learning is the day you need to change your profession.