Do you mean manage them all together or one by one. If you want them one by one then just login and use em, they wont ban your IP in this case tho.
Excel or google docs - might want to stick with excel since there's speculation google will look into your files (google owns youtube).
But since it's a relatively small project (assuming) either one shield be fine.
If you don't know how to use either, youtube is your friend.
If you want them one by one then just login and use
What is em ???
this work.I own 10-15 account in my own IP. You can do anything youtube dont mind as long as your not doing anything wrong and also you need a multiple cp number for verification.
Create a set of VMs or/and different browser profiles for each account. Proxy for each account is good too. Opera+VPN or Chrome + VPN etc.
maybe what him want ask is to manage them simultanely this 10-15 account, maybe upload same videos or different videos on this 10-15 account, i hear there are software for this. this maybe him want to ask because ofc it's easy to enter on this account and use them ^^