Line 37 is for a tax due. Your AGI is on line 11.
COMPARE JOINT TO MSF
To compare Joint to MFS. If you are using the Online version, do NOT change anything on your return. You would have to start with a new account and do a test return. You don't have to pay unless you want to print it out. So you might need 3 accounts, one for Joint and two MFS, one for each spouse.
How to Compare Joint to Married Filing Separately
https://ttlc.intuit.com/community/married/help/how-can-we-compare-married-filing-jointly-with-marrie...
How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
It would be better to use the Desktop CD/Download program. It can do unlimited returns and has a What If worksheet to compare them and many other advantages over the online version.
You can buy the Desktop CD/Download program here
https://turbotax.intuit.com/personal-taxes/cd-download/
