What you are doing there is setting the colour for objects to be drawn on particular layers with particular names.
Just calling a layer 'Text' and setting its colour will not change the colour of all text, just text (and most other objects) that you put on that layer that has its colour set to 'bylayer' (rather than set to a particular colour or byblock).
All objects, not just text or dimensions, can have their colours set in various ways.
Taking the colour of the layer it is drawn on is just one way, and does not work for all types of object.
Some objects such as dimensions or blocks will use their own internal settings.
It seems that you want to change the colours of elements within your new dimensions?
To do this you have to create a 'dimension style' and set the colours of the elements within this style.
You can have various dimension styles with different settings for text and line colours, text fonts, arrow types, dimension scale, etc.
You then pick which dimension style you want to use when dimensioning objects.
I assume that you are teaching yourself to use Autocad, have you accessed any tutorials yet?
You do realy need to have something to refer to, and to teach you the basics, just as with anything new you want to learn.
We no longer have a tutorials section as such on this forum but I would point you over here, where there is a good collection of basic and advanced tutorials. (As well as a busier help forum than this one).
You can find a few good suggestions for books and on-line courses here:
This could also be a help
(For instance look up- User guide > Annotate drawings > dimensions and tolerances > Use dimension styles).
It's the 2010 user documentation but still applies for 2016.
Good luck on the journey learning Autocad, but please use some of the tutorials, and maybe consider taking a short training course.
If you start with understanding how to do things the right way it will save you endless trouble in future when you have to go back and modify things.