When I completed my taxes in 2017, I opened a HSA that I funded in 2018. This amount shows on the 2017 column. I have not funded the account further. What should I do?

If you made the 2018 contribution for 2017 directly to the HSA custodian, then when you go through the HSA interview and see the screen "Let's enter [name]'s HSA contributions", do NOT enter these contributions, because they would be reported by TurboTax in 2018 (which you already know would not be right).

Instead, you should have reported your direct contributions made in 2018 for 2017 on your 2017 return (did you?). If you did not, then you need to amend your 2017 return. See the description under "Form 8889" at https://www.irs.gov/publications/p969#en_US_2017_publink1000204077 (note: this is for 2017 because the 2018 Pub 969 version is not ready yet - but the rules are the same, just update the years).

If, on the other hand, you made these contributions through your employer, then when you see the screen with the heading "Did your employer tell you about any other contributions?", then answer "yes". Three new lines will appear and you will enter the amount of the contributions on the line "employer and payroll contributions made in 2018 for 2017".

This will cause form 8889 to be updated correctly.