Clearblue digital OPK test says use FMU but others say that will give you false positive and to test in afternoon. Which one do you use??

I've seen many people say to test in the afternoon but others use FMU. I'm using the Clearblue advanced digital OPKs and the box says use FMU but others say that will give you a false positive and to test in the afternoon or even test twice a day with those. They aren't cheap and the cheap strips I have have been using are confusing for me and not yet any positives or close to positive. So the Clearblue is easy for me to understand and simple. Should I just be testing twice a day morning and afternoon or just the FMU or just afternoon? I'm just wanting to hear experiences from you other women that have used them and what you guys did. Sorry for long post just trying to figure out which one to do to get best results!