Does You Subwoofer Settings ??

Do most find that subwoofer settings are not perfect for every song you play ??

Yes

Last year went to a SVS SB16 Sub and 95 percent of songs it sounds beautiful. But other songs has boomy sound

Boomy bass is a room acoustics issue. Your room will have standing waves, aka nodes, the frequency of which will be dictated by the distance between parallel surfaces in your room. What ever that frequency is, some recordings will have more energy at that frequency than others, which is why the issue can be inconsistent.

Room treatments, multiple subs and e.q. can all be effective tools in the battle. In my personal experience, I have found out that if I notch out the offending frequency with PEQ in the worst offending songs, that the songs that weren’t plagued by the issue have not been affected. Probably because that frequency wasn’t in those songs with enough energy to have been noticeable in the first place.

I have a pair of SVS SB 1000 Pro subs.  One of the things I like about SVS is the app.  I adjust the volume of the subs occasionally depending on the music I’m listening to.  I don’t adjust other settings since they are set by the preamp and sound good in my room.  

Just reading through this and noticed a mistake in my post - I meant lowering the crossover frequency, as pointed out by @carlsbad2 

Just to expand on @deep_333 suggestion,

If I'm not mistaken the SVS App includes three presets. These presets should allow for personal customization of all or most of the available App settings to memory.

They may already have factory settings that you may find beneficial towards your issues. Dig deeper into the App or contact SVS for help. All the best with it.

Room acoustics issues are static, more or less, and variances are most likely in individual recordings, particularly if the differences are in quality, e.g. definition not just qiantity. Also, If you are listening at only 75 dBA, you're also well within Fletcher-Munson loudness curve territory. The ear at that loudness is decidedly non-linear and changing the volume even a few dB will change the ears linearity, especially ar low frequencies.