I have very dim headlights since I purchased my.

You didn't say if it has been like this since new or since last week. If it has been like that since it was new, there are some models that are well-known for having a poor head lamp design. The wrong bulbs would not be a consideration. The aim could be wrong too but that would not be common. You can tell that by observing where they shine on the wall of a building, and where the beams go as you back up.

Older plastic housings can become yellowed with age. There are kits that claim to remove that haze but I've never used them and haven't heard if they work.

Look in the owner's manual for the part number for the head light bulbs. The most common one is a "9004". There is a different one that looks almost the same, (9007, as I recall), but the filament is turned sideways and is supposed to reflect off the side of the housing. I think the sockets are the same so the wrong one could be installed.