Why does ETrade keep making my cost basis $0 and using the adjustment column instead? (when filling 1099B?) It happens even if I put my own cost basis. Thanks.

Did you upload your 1099-B? If so, and if this issue keeps presenting, you may need to delete the uploaded 1099-B and enter it manually. 

Does it matter?

As long as the gain or loss is reported correctly, go with your broker's numbers.

This is what is reported to the IRS.

while it may not matter if you are concerned contact e*trade to find out.  there may be a problem in the way they set up the export.    the simplest way to tell is to go to your e*trade a/c and look at the actual 1099-B if it actually shows the adjustments - go with it.   if not you MAY have a problem because what e*trade sends the IRS won't match your reporting.  I  would think this would only happen if you transferred items into the account so e*trade can't verify your cost basis.  but this is only a guess.