I work in marketing, so I often see stats that reference smartphone penetration/usage.

Which of the following is correct? I've seen both.

65% frequently check items on their phone while in-store

65% frequently check items on their phones while in-store

What about:

Their confidence, camaraderie and try-it-once attitudes define every aspect of their lifestyle.

Their confidence, camaraderie and try-it-once attitudes define all aspects of their lifestyles

And:

Chinese male millennials depend heavily on their phones when shopping in-store.

Chinese male millennials depend heavily on their phone when shopping in-store.

Or:

65% say their phone is the most valuable tool when they’re in-store

65% say their phones are the most valuable tools when they’re in-store

Please help, this is so confusing! I, for the most part, get collective subject and plural/singular verb usage, but am often confused about the plurality and singularity of the object nouns.

Thanks in advance!