There is some change in the salinity of the oceans over a geological time-scale (thousands of years), but in general the oceans arent getting significantly less salty, even with more freshwater input. All the salt in the oceans comes from land: small particles of salts that are leached and eroded away from the landscape. In a river, the salts get constantly washed down into the earth or flushed away to the ocean. We only notice the saltiness in the ocean because the salt particles have no where to go and they become concentrated. So even as glaciers melt and rainfall patterns get wacky with climate change, the salts in the land still get washed into the ocean.

I can think of one way to make the oceans more salty.Maybe you can think of more ways.

1. Water in the ocean evaporates and turns into a gas or water vapor in clouds. The salt stays behind in the ocean. Some of the clouds move over the land and come down as rain, which runs into rivers, which flow into the sea, and the whole cycle starts again.

Maybe the oceans are slowly getting a bit less salty, too. I don't know. I'm sure they aren't getting a lot less salty, or I would have read about it when I read about oceans and climate change.