Planned Depreciation Computation after Asset's Life was changed

Hi SAP Gurus,

We have this Asset Voyager with Acquisition Cost of USD11,224.49

Useful Life is 3 years. However, on October 2015, we changed the useful life into 5 years

Start of Depreciation is March 2015. See attached Depreciation Key.

Status          Fiscal Year     Fiscal Month     Depreciation

Posted          2014               March 2015     -311.79

Posted          2015               April 2015        -311.79

Posted          2015               May 2015        -311.79

Posted          2015               June 2015       -311.80

Posted          2015               July 2015        -311.79

Posted          2015               August 2015   -311.79

Posted          2015               Sept 2015       -311.79

Planned        2015               Oct 2015         -576.02

Planned        2015               Nov 2015        -184.96

Planned        2015               Dec 2015         -184.96

Planned        2015               Jan 2015          -184.96

Planned        2015               Feb 2015          -184.96

Planned        2015               Mar 2015          -184.96

Question #1. How does sap computes for the planned depreciation in October 2015 -576.02  and Nov 2015  184.96???

Question #2. What depreciation key should I use so that SAP will use the remaining useful life of the asset which is 7years?

Thank you!

Sincerely,

Athena