Bass traps in the corner is correct.
Panels on the front wall may be correct. There purpose is mostly to prevent reflections from your speakers coming to your listening position so if you imagine a sound 'ray' departing the inside corner of the speaker to the front wall, then reflecting to your chair, the panel should be where the ray hits the wall. You can use 'the mirror technique' to find that position. Sit in your listening chair whilst someone moves a mirror on the wall until you can see the inner corner of the speaker - the panel should be placed to cover that point.
Side walls. Use the same mirror technique to locate the point of contact of side wall reflections direct from the mid/HF drivers. Find this point on each wall for both the sound coming from the left, and right speakers - that is, two points on each wall. You can then try the panels in those positions, or instead, try a diffuser.
Your panels may just absorb but they may also have some diffusor type mechanism in them - a scatter plate for example. Diffusers throw some frequencies in all directions to give a more lively sound (whereas as absorbers deaden the sound). You should experiment with their positioning, perhaps on the front wall instead of the panels, or on the side wall. Any spare absorbent panels could be placed on the back wall or even across the back corners. Diffusers may not do much on the back wall.
