Baofeng, Pofung, Dual Watch
Baofang / Radio won't access Band B when A/B key pressed Dual Watch is turned on. There are two settings that control this functionality. You select the combination that you want.

1) Dial Watch Enabled - with this turned on your radio receives on both the A and B bands. With it off, the radio receives only on the active band (A or B)

2) TX Dual Watch - With this off, you are able to move between A and B bands. With this turned on along with Dual Watch Enabled, you will not be able to move to the other band from the face of the radio. This one turned on without Dual Watch Enabled seems to have no effect...

So, Dual Watch Enabled works by itself so that your radio will receive on both bands; however, you will not be able to make any changes to the "other" band (this could be A or B depending on the setting for TX Dual Watch) if TX Dual Watch is set to something other than Off. This could be a good thing that would help someone from changing away from a preset channel. If TX Dial Watch is set to Off, you will be able to make changes to both bands.

So, make those changes to your file for these two options to get the functionality that you want.