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+ knock vs - knock

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what would be the cause or difference between a + reading and a - reading. which would be worse to see?

I don't understand your question. Can you tell us what engine, ECU, and/or software you are using? What does "+ reading" and "- reading" mean?

Do you mean a higher value on a particular channel or signal? If so, what is the channel/signal name in your software or documentation?

Are you measuring a voltage with voltmeter or oscilloscope?

the car is an 15 sti EJ25 on a cobb access port tuner. i am getting a -1.40 to -3.40 knock reading as a norm but from time to time i am getting a reading of .85 knock reading with no - and it is set as it is the high reading so i am assuming it would be considered a +

I don't have any experience with Cobb, and this page doesn't refer to any channel named just "knock":

Subaru Knock Monitoring

It seems like what you might be describing is Feedback Knock Correction, or Feedback Knock Learning and if so, then those values represent the amount of timing adjustment. I would expect a negative number to be retarding timing, and a positive number to be advancing timing. it seems like large negative number would be of a concern.