Convert 5 to 6 net names problems

I converted a large board from V5 to 6 with problems.
I do not understand net names. I have GND, /GND, /R2-1/GND,/R2-4/GND. Under V5 the grounds were one net. /GND
Under V6.0.7 they are separate.
Layout; The component pins are all “GND”, and will not connect together.
I also have this problem with +5V, +12V, -12V and most Filled Zones.
Making net name changes in Layout is temporary. (not the thing to do)
I think GND is different on each schematic page.
Thanks for your help.

Your GND symbol is probably not marked as a power symbol.
Power symbols are effectively global labels and so they will connect to each other on different sheets.

Your situation sounds like different sheet GND are different nets.