You have to use a flag tag, in the "data" tab under "Data source" in the "Treat As" drop down, select "Bit Array Little-Endian" then you can select the "Bit Number"
My screen shot is from a Redlion connected to a MicroLoigx. Yours is from one connected to a CompactLoigx.
Since the OP was using PLC/5 or SLC500 addressing I used a screen shot that would show how to set it up clearly for him. I was originally going to use this screenshot from another post but decided to post a new one that was less confusing for the OP. Hope that clears things up.