Just got my new dentures. the rise in the pallet is high but the part over my tongue is not as deep making speech very hard. should it be deeper?

It would be prudent to consult your dentist as the issue requires an in-person evaluation. Wish you good health!

Dentures are fabricated with tight tolerances... a balance between strength and comfort. You just had the prosthetic inserted. Give your mouth (and tongue) a chance to adapt. I would venture that if you used a caliper to measure the thickness in that area it would only be 2 to 3 mm thick. Too thin and the denture would easily crack. Have your dentist explain further if more info is needed.