Help please we have a 98 Oldsmobile 88 try to start and it does nothing

What is your question?

We were told it was the starter so we changed it two weeks ago and it's still does not want to start and now I can't turn on my brights my radio I can turn on and it cuts in and out the Volume goes down you cant hear it and now it's happened about three times thhe security light came on and stayed on and when I tried to start it it does nothing finely I got it to start 30 mins later after trying everything

What makes this problem better or worse?

It seems to help shaking the key or turning it back

How long has your 1996 Oldsmobile 98 had this problem?

Mouth and two weeks