This is the first year i'm inputting my K1 in turbo tax, do i need to input all previous year's K1 into turbo tax in order for them to accurately calculate my gains and losses?

[MinhT]

No, you should only enter this year's Schedule K-1 on your 2018 tax return.

If you had Schedules K-1 for past years, you should have reported them in the corresponding years' tax returns. If you did not report them, you should amend your past years' tax returns to add them.