Are you using the Online version or the Desktop program? Desktop can do several returns so you can compare.
You can not compare that in the Online version and really can't do that in the Desktop program either. If you are using the Online version don't go changing it around. It won't work and won't give you the right results. And it will mess up your account and return. You just can't change from joint to separate. You would also have to delete all one person's name, info and income. Then do a separate return for them. For Online you would have to set up 3 accounts, 1 Joint and 1 each for both of you separate. You don't have to pay unless you want to print or file.
If you have the desktop version you can do a What-If worksheet. Go to Forms Mode (click Forms at the top) and click Open Form. The What-if form is near the bottom of the US1040 listing (you have to hunt for it). You can play with that. There is a check box at the top to compare MFJ vs MFS. You should save your return with another name and work in the copy. And you can also make up two separate test returns for each of you to see.
