I am filling as a dependent this year and want to use my 1098-t from 2020. I have older 1098-t as well and was wondering if I could claim if I was a dependent those years

[naalvino]

I have years 2018-2019 that were unclaimed by my parents (they were unable to claim), can I claim them?

[xmasbaby0]

What?   You seem confused.   If you can be claimed as someone else's dependent, then the 1098T goes on the tax return of the person who can claim you.  If you are someone else's dependent you cannot get education credits.  And....you cannot use old 1098T's on a 2020 tax return.  They can only be used for the specific tax year for which they were issued.

[Hal_Al]

You say you are filling as a dependent this year.  Did you mean to say you are filing as a non-dependent.   Only a non dependent can claim a tuition credit.

You can NOT claim your 2018 and 2019 1098-Ts on your 2020 tax return.  They can be only claimed  in those years and only by the person whose dependent you were.  If they didn't qualify, the credit/deduction is lost.