I have to say your orchid looks very cute the way they turned the spikes into a shape. I should try that on my next spikes.
The yellowing leaves are usually due to dehydration as a result of underwatering or overwatering (root rot) or natural process of aging.
Did this plant have all four leaves green when you bought it?
I don't think the overwatering is the issue here because you mentioned that the media was not wet when you checked it. Was it completely bone dry though?
The white decorative pot probably has no drainge hole, right? It can be a problem only if you water too much.
What media is the plant potted in?
If it's in bark, then you can just take the whole pot to the sink and drain it after watering. If in moss, you can be carefully water just to keep the moss moist.
If this seems all too confusing, you can just take the plant out of that white pot and put the plant in any other pot with a drainage hole on the bottom.