CCS: ccv7

Friedrich Prof. Dr. Bloedow said:

And now I cant change the value of  unsigned char in the "Expressions"- Window.

Sorry but I'm not clear on what you are trying to do in the expressions view. Are you trying to change the format of a variable or cast it to another type?
An example or screenshot that shows what does not work would help us better understand the question. 

It is for TMS320F28062

I tried this with CCSv8 and a F28069 and cannot reproduce the behavior you are reporting.

When you try to change the value are you clicking on the Value field and entering the new value?

Please see my screenshot below. I found that if I select just the hex portion of the Value, say 0x002 for array[0], and try to change it it does not change.
However, if I select the entire field and enter a new value, it works.

Could you show us an example that does not work for you?