Even thought they look really similar and convey pretty much the same message, the timing of their usage makes them just different enough to feel different.

Let’s say we take those sentences and make similar ones in English. I dropped the Albert?as it kind of forces a prior question or wider context.

Je trouve

Making a point:

De nous tous, je trouve que c’est celui qui a le moins changé depuis des années.

Of all our friends, I find he changed the least.

Similar example

I find this site is really useful.

Je trouve ce site très utile

Je me dis

Similar to self-thinking as je me dis = I tell myself

(Skipped as hard to do 1:1 translation)

Similar example

When I’m scared I tell myself that everything will be ok.

Quand j’ai peur je me dis que tout ira bien.

Je pense que

Stating an opinion:

De nous tous, je pense que c’est celui qui a le moins changé depuis des années.

Of all our friends, I believe he changed the least.

Similar example

I believe this answer is the correct one.

Je pense que cette réponse est la bonne.

If those seems to be different to you (they do to me at least) then that’s pretty much how the french ones sounds to many of us (different).

They do have enough nuances to sound different

‘Je trouve que’ puts the emphasis on the fact that you find that Albert hasn’t changed a lot. It doesn’t express doubt regarding your opinion.

‘Je me dis que’ is something you say to yourself, which doesn’t count as an absolute truth. You’re pondering the possibility. It’s more like a possible truth.

Lastly, ‘je pense que’ is a very careful way of expressing something you think might be true, but the word emanates incertitude.