Hor do I repair seams that are lifting on our kitcken counter?

I take it your counter is laminated, not a solid surface?

For most joints it is just a matter of getting underneath and adjusting the bolts called 'dog bones', they are shaped just like the name,a nut on each end and threaded shaft in the middle, when you tighten the threaded shaft, both nuts tighten.

Hope this answers you question,

KBC

if you can't reach the bolts take a hammer and a 1 1/2" bolt of wood, (2x4) and try and tap the high side down

Once again both are correct. However do not hammer directly on the counter, place a block of hardwood down and hit the wood. If you can reach under and hold a brick or large hammer againist the lowside it will shift more quick.