I do not know why TurboTax choose to print your return on 1040-SR rather than 1040, but it doesn't make any difference to your taxes - the forms have all the same lines and boxes (as I think you know).
I seem to remember a box where you could check the 1040-SR, but I can't find it now. Oh, wait, this is maybe it.
Go to Other Tax Situations->Miscellaneous Forms->Request an alternative media preference, and click on Large print. In your case, you might try to click Standard print (cancels any previous preference).
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