Probably you are accessing our (or any) Teamspeak3-server from different computers or systems. There is no more "login" and "password" used for authentication, as it used to be on Teamspeak2. Instead of that, Teamspeak3 uses "unique identifier". This is generated by Teamspeak-client to each user automatically. Quite naturally, Unique-ID's generated on different systems/computers are not the same. But you can transfer your Unique-ID:

1. In Teamspeak3-client click on Settings > Identities
2. Select identity you want to export (usually Default)
3. Click Export on the upper right corner
4. Choose a filename where you save your Unique-ID
5. Start your different computer/system
6. Go to Settings > Identities
7. Select identity for which you want to import Unique-ID
8. Choose Import
9. Point to the ini-file where you exported your unique-id

This will allow you to receive the same permissions settings assigned to you by the server, regardless of which PC/system you are using.