Ok, finally found this.
To make the text editor wider, it is in style folder - Standard form (tall version) - qa-form-tall-table. There you can make the whole thing wider.
To make the question title box and tag box wider also it is; qa-form-tall-text
There is also: qa-form-tall-data, but I am not sure what that is for, I did pay around with it but did not see any changes so I left it as it was.