Increasing bass on floor standing speakers

I used a polarity tester and the woofers are on the same phase. The tweeters were giving inconsistent results... One alternated with every pulse, the other was a little more random. I assume I wasn't using the app properly (I played through one phone connected to the amp and received with another. Used different frequencies and the L R fader.)
I'll rewire it with thicker internal wires when I know if I need to change any polarities. 

The speakers are new to me so I'm not sure if the sound has changed over time. 

Speakers on the long wall, I'd guess not much space behind the listening position then? 

Sounds like a perfect case for bass (wave) cancellation. 
If not quite that, figure out about any 'other' unintended bass traps in your listening area. 

I had this issue and only found out once I moved to another location. It can be subtle but annoyingly effective.
I know now. 
Bass problem, in the new location (speakers on short wall), gone like magic. 
Michélle 🇿🇦 

I'm a novice although I purchased my first equipment in the 70s while overseas in the military. I now merely have a Yamaha N803 receiver and Vandersteen 1B speakers that are about 25 years old. I stream Spotify and have it set too the highest quality. I will probably upgrade but for now, I'm pleased that I kept the cost down, and most of my listening is background. I'm considering new speakers, probably from World Wide Stereo in Hatfield, Pa. near my home.  I heard and like their Focals.  Would I be wasting money with such a modest receiver or could I improve my sound considerably with new speakers.  Thanks for any advice.   Doug Hess, Newtown Square, Pa.

If you can, put speakers on the short wall, not the long wall. Start there. Find listening position with the best overall response. Tweak from there.