Question about modes

I have a question about modes. If I want to improvise over a C5 or Cmaj chord and want to play in the Locrian mode. Should I be playing the C Locrian mode, or should I be playing the B Locrian mode due to the fact that B is the 7th of the C scale. I know how the modes are formed and such but for some reason all my improv seems to just end up sounding like Ionian. Am I using them wrong? Am I just not emphasizing the B notes enough? I watched some videos of the different modes being played over a droning root note and the colors of the modes sound vastly differently when I attempt to play them

Sounds to me like you understand the basic concept fairly well. You can use B Locrian, however, to avoid sounding Ionian (i.e. Major) stop playing Ionian. You will notice that many guitar players will use inflection notes, or notes not in the key or chord to reduce the unsavory sounds of repetition.

I don't think I fully understand. You say that I should stop playing in Ionian. So over a C5 chord, if I'm playing the B locrian that means I am still playing in Ionian correct? But if I continue to play in B locrian and the CHORD changes to B5 I am no longer in Ionian correct?

So if
-Ionian - C D E F G A B C - sounds major

For locrian should I be playing B C D E F G A B = B locrian
OR
Should I be playing C D E F G A B C But with the locrian intervals.

The end result is that I want a locrian colored solo over a C5.



Also I know locrian is a diminishy scale and probably won't sound as nice as some of the others over a C5 for these are just for the sake of examples of how to get to my end goal.

The intervals are what gives a particular mode its tonal qualities. The B Locrian mode corresponds to the C Major Key, C Ionian Scale and Bdim or B-D-F. If you count the intervals in the chord, you will notices that the fifth is a "flat" fifth and thus, diminished.

You are looking too deep into this. The diminished fifth is what makes the Locrian sound "Locrian". So emphasize that note and you will achieve the tonality your are searching for.

Also, Locrian doesn't sound as "nice" because the ensuing triad is dissonant.