I'm trying to report my cryptocurrency sales. I bought BTC on a single day, but sold on two different days and I'm having trouble with the cost basis.

There are a couple of ways you can solve this issue.  First is if CashApp can supply you with Form 8949, showing sales, basis, and status as to long-term or short-term, or both.  If not, you should first delete the entries made and follow below:

 

If you know the actual cost basis you can adjust what CashApp says by follow these steps:

1. In the "Wages & Income" Section click on "Show more" or "Edit/Add" at the "Investments and Savings" line.
2. Click on "+Add investments", then continue.
3. Click on "Enter a different way"
4. Click on the box for Cryptocurrency, then continue
5. Click on "Type it in myself"
6. Enter the payer's name, etc., click continue
7. Answer no if you did not get a 1099-B as it appears from your question.  If you did get a 1099-B the procedure will be slightly different.
8. Enter the remaining information as you know it to be if you did not get a 1099-B
9. Answer the remaining questions and you will return to your investments and savings summary screen.

The procedure is somewhat different if you did receive a 1099-B.  The steps are the same as steps 1 to 6 above. Step 7 is where the difference begins:

1. Answer yes if you received a 1099-B, answer the following boxes no, yes, no, then continue, and continue again
2. Enter the information for proceeds, and dates. basis per your statement, and then put a checkmark in the box below cost or other basis saying that the cost basis is incorrect.
3. Next screen is normally none apply
4. Next screen place a mark in the circle that you know your cost basis and need to make an adjustment and then enter in the box that appears your basis as you have it.
5. The summary screen may appear to not take the adjustment but look at the gain or loss number and it should agree to what you have and click continue
6. You now should have returned to the Investments and Savings summary page.

 

@mxnstrs