Another dimensioning problem!

I am experiencing a problem where the dimension text becomes so small it is unreadable.  I tend to draw in real size and then make the dimension text big enough to read using Options/Current Drawing Preferences/Dimensions.  For example I am drawing up my front garden (9m x 14m) and setting the dimension text height to 250mm.  When I close and reopen the drawing the text size has reset to 2.5mm.  BTW the extension line offset has also reset but the arrow size remains set at my input size of 250.
Any help would be appreciated.

Version: 2.1.3
Compiler: GNU GCC 4.9.1
Compiled on: Sep 23 2016
Qt Version: 5.4.1
Boost Version: 1.60.0
System: Windows 10

Did you save the drawing after having changed the dimension settings from default to your settings? I can't think of an other reason for being reset after closing and reopening the drawing. Or you might have opened one of the back-up files instead (#,~).
Drawing in real size is the proper way.
BTW if you set General Scale to for instance 100 in your case, you can leave all other values to default. They will be adapted automatically behind the scenes.

Dellus.   Thanks for your prompt comments.
Yes I did save and I opened the same file using /file/recent files/....... so I don't know why this happens.
Thank you for the tip about the General Scale.  I will certainly try that as it should be very useful.  I've only recently started using LibreCAD so still getting used to all of its features.