Water Softener, now yellow stains

We have a water softener using potassium. We used to have the familiar white calcium stains on the faucets and spigots. After installing a water softener, now we have yellow stains on the faucets and spigots and toilet bowl! They're slightly easier to clean off than the white calcium stains were, but the whole reason why we installed a water softener was to completely get rid of this kind of cleaning maintenance!
What's happening?

stains

Hard water leaves calcium deposits. Softening the water exchanges the calcium for sodium or potassium. It does not eliminate the staining, it merely changes the type of stain. Calcium leaves hard to remove stains while sodium and potassium leave water soluble stains.

Yellow staining usually is caused by iron in the water. Softeners remove iron IF they are sized correctly based on the peak demand water flow and capacity required.

All softeners can use sodium chloride softener salt ot potassium chloride salt substitute except you have to set the salt dose higher to use potassium. If you don't get that right, or the SFR sizing, then iron and hardness will get through the softener, causing water spots or stains.