One of the AxesLabel is "$:\text{log}|\Phi8b(u)|\color{Red}{\text{Red}}$".

Question: How to make it like: "$\color{Red}{\text{Red}}:\text{log}|\Phi8b(u)|$"?.

My Mathematica commads:

Φ8[u_] := Sin[u]; 

Φ8b[u_] := Sin[u] + 1/10; 

Plot[{Log[Abs[Φ8[u]]], Log[Abs[Φ8b[u]]]}, {u, 0, 2*Pi}, 
  PlotStyle -&gt; {{Thick, Blue}, {Thick, Red, Dashed}}, 
  AxesLabel -&gt; 
    {u, {Style["Blue", {Blue, Bold}]*":log|Φ8(u)|", 
         Style["Red",  {Red, Bold}]*" :log|Φ8b(u)|"}}]



Question: Criteria is plural, of course, but
Answer: According to this article at grammarist, criteria is gaining traction as a singular noun, and appears in that role in notable publications.


  Although criterion lives, criteria is gaining ground as a singular
  noun, as used below:
  
  Careful though… this criteria is a double edged sword. [Schriever Air
  Force Base]
  
  The only criteria is that it must be partially or completely open to
  the public. [Houston Business Journal]
  
  Dark matter is another criteria that is examined. [Universe Today]


Based on this, I'd not deem If Criteria B is negative... to be incorrect. 

Purists would prefer If Criteria B are negative..., though, in my opinion. The Oxford dictionary still considers the singular usage a 'common mistake'. 


  Strictly speaking, the singular form (following the original Greek) is
  criterion and the plural form is criteria. It is a common mistake to
  use criteria as if it were a singular, as in a further criteria needs
  to be considered.


Which one you should use depends largely on the audience. I'd say go with the singular, which is more widely used and isn't outright wrong; unless you have reason to believe your audience is likely to frown upon the controversial usage of the singular. It's like deciding whether you'll end a sentence with a preposition or not.