Confused with those sentences! are they correct,is there any grammar mistake?

[rayafadil]

I was revising English Grammar, then I wrote this:

Nowadays Children are able to login at any computer and google anything they want,while old people were not able to do this when they were children.Old people never have(had) had the experience to use computers because they were not available at that time.

[PRINCE SINI]

I was revising English Grammar, then I wrote this:

Nowadays Children are able to login at any computer and google anything they want,while old people were not able to do this when they were children.Old people never have(had) had the experience to use computers because they were not available at that time.

Nowadays Children are able to login to any computer and google anytime they want,while old people were not able to do this when they were children. Old people never had the experience to use computers, because they were not available at that time.

THIS IS ANOTHER WAY OF WRITING SUCH GRAMMAR.
Nowadays children can login to computer and google anytime they want,while in those days the older ones did not have such opportunities. Because then, there was no computer.

[PriligyMai]

nothing else needs