I rolledover a 457 roth accocunt to my main roth account so I couldincrease investments options. Why is the amount of the rollover included iin my AGI which is now going to increase my medicare premiums

Such a rollover would be reported on a Form 1099-R that has code H in box 7.  A Form 1099-R with code H in box 7 is required by the IRS to have a zero in box 2a.  Some payers fail to put the required zero in box 2a, causing TurboTax to mishandle the reporting of the distribution.  If box 2a is blank on the code-H Form 1099-R provided by the payer, enter a zero in box 2a of TurboTax's 1099-R form.

(If the distribution was from the traditional account in the 457(b), a direct rollover to the Roth IRA would be reported with code G and would have a taxable amount in box 2a of the Form 1099-R.)