It could be multiple things going on. That top one on the right hand leaf looks like sunburn. But it's indoors, right? The leaves with more defined spots look like insect damage, like mites. Check under the leaves. Look for any sign of fuzzy spiderweb type stuff. If it's insect, spray with neem oil.
The bottom could be too much water in the pot.
I'm sure some experts will be along shortly and correct me.. lol