i have just bought i phone 6 plus before that i was using 3gs. i am using the same laptop but know it is asking for authorization

Hi there pje044,

Welcome to Apple Support communities.

If I understand correctly, you're concerned about an authorization alert that appears when connecting your new iPhone 6 Plus to your computer. Are you seeing a ‘Trust This Computer‘ alert? Try taking a look at the article below which outlines the ‘Trust This Computer‘ alert and it's usage.

'Trust This Computer' alert on iPhone, iPad, or iPod touch - Apple Support

Ciao.