Well you just select the QR Code object and set the data accordingly! But I'm guessing this isn't what you you wanted to know.
Unfortunately, you can't open a PP3 template in PP7, so you'll have to recreate it with PP7.
Alternatively, you can contact your reseller to see if you can obtain a trial version of PP4 that would allow you to save the PP3 forms in PP4 format, which PP7 can read.
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Technical Product Manager
I don't want to achieve immortality through my work; I want to achieve immortality through not dying - Woody Allen