n80
Yes, moving your chair away from the rear wall, typically DOES improve the sound for the same reasons that moving the speakers away from the front wall does. It's all about how the sound from your speakers interacts with room boundaries, walls, ceiling, etc........yes, your speakers will seem to have more bass when in or near corners, the corners acting to concentrate and reflect the bass back into the room, but the result is exaggerated low frequencies, not a true reproduction of the music........Something to keep in mind is that when you get used to hearing things a certain way, your brain thinks it's right. When you initially change things, it often doesn't sound "right", even though it's actually better, because it doesn't sound like what you've gotten used to.
My speakers weigh in at 100 pounds each and are spiked also, so yeah can be a PITA to move them. Something I did to alleviate that problem is to make pads for the spikes from 1x4 oak and stuck self adhesive felt furniture strips on the bottom. I have hardwood floors, so it makes it fairly easy to slide them around. Carpet would require a different version, but it could still be done easily enough.
My suggestion, especially since you're just getting into this, is to spend some time googling room acoustics, room treatment and speaker placement. There's a lot to learn, but it's not rocket science once you get the basic concepts. You may find differing opinions on things, but in the general sense they'll be in agreement. Ultimately what and how much you'll be able to do in YOUR room will depend on how the room is laid out, how it's typically used and of course how amenable "mamma" is to your new hobby.
As previously mentioned, EVERYBODY in this hobby has an opinion about what's "best". Take it with a grain of salt because there are a lot of variables between rooms, systems and listening preferences.
The bottom line is that speaker placement does matter significantly, as does listening position, as you've already discovered. What works best in your room will take some time and experimentation to determine...........You're new to the hobby, read as much as you can and there's a ton of free info out there.......Take opinions for what they are, opinions. Some will be useful, some won't......A mediocre system can sound very good when properly set up. A very good system can sound poor when NOT set up properly.....I have a pretty good system, but for years I had it set up poorly due to lifestyle factors. Once I was finally able to set it up optimally in my room the difference was night and day. Made me sad to realize what I'd been missing for so long.
It's a fun hobby that can, but doesn't have to be terribly expensive. You already have a good starting system for essentially free, if I recall. Educate yourself and do what you can to optimize what you have . You can always make improvements as you go along.........It's a hobby, have fun with it