Retirement tax questions

You can edit the form.   

In TurboTax Online - Search for 1099-B and use the Jump to link.  Select the down arrow and then click on Edit.  See image below

In TurboTax Desktop - Search for 1099-B and use the Jump to link.   Select Review, then select the pencil icon to edit your 1099-B.

Put a checkmark in the box that says The cost basis is incorrect or missing on my 1099-B if you need to adjust the cost basis.