Basically a world that cannot be mapped.
Sure you could have an ocean. Maybe icebergs floating around. That would be fine. Very serene. Walruses. Or you could have a
Chunks of solidified rock bob thru the molten lava, smashing into one another! Volcanos rise up from the core thru the lava and spew hotter lava and clouds of sulfurous ash. Meteors splash down! Need I mention lava monsters?
All planet is ocean with floating islands!
In Russia there is Kravtsovo lake with natural floating isle made from turf.
Since isle is changing its place every few month, mapping it is wrong approach. Imagine, that majority of surface of your planet is ocean with islands like this.
Any planet with a thick, turbulent atmosphere will always appear different on the surface. For example, the gas giants may have consistent belts / zones of gas, but individual storms appear and reappear constantly. Arguably, a very windy would could experience much more visual variation, resulting in an ever-changing surface.
For example, look at Neptune's immense Great Dark Spot, a storm larger than Earth which only marred Neptune's surface for ~5 years.
If you don't want your world to be a gas giant, check out our neighbor Venus. While we can map its surface with radar, the atmosphere is the only part that's visible to the unaided, optical eye. Since it's constantly changing, we have few visible light maps of Venus, and none that stay accurate for very long.
when you say changing the appearance of the planet and reforming it, it makes me think of displays that change colors. maybe putting them on lifts that move them up and down randomly. making the surface look like a blocky colorful sea. Or a vast swarming sea of nanites assembling different shapes with colors and constantly reshaping and changing them. this is the technological option, however nanites are a bit handwavium, since they don't and may never exist.