Please, can you check the values for 
General Scale and 
General Factor in Dimensions Tab of Current Drawing Preferences.
General Factor affects the value of a dimension and 
General Scale affects the size of dimensions text, arrows and extension lines.
When you say the dimensions should be much larger, what are the exact numbers you expect?
From the image we can see that the ratio of diameter dimensions and linear dimensions doesn't match, have you changed diameter or linear dimensions manually?
Armin
	
	
	
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