Bought a place recently and tiles look like this: https://ibb.co/891c6cM Can I fix it myself? How should I do that?
Floor or wall? Looks like you're getting substrate movement. You can fix it. Dremel makes special bits. The cheap manual rake saws can work well too. If it's floor tile it'll just come back though if it's due to too weak of a subfloor.
Floor
However when I sweep my finger on those grouts on the tiling on the wall, I see whitr dust on my finger.
Tile grouts will crack over time. That’s just the nature of it. Just get a small bag of mixture at Home Depot that matches the color of the current grout. Apply over the current grout and let it dry out. If you want to make it look good and uniform though, you will need to regrout the entire section.
Putting it over old grout is a bad idea. The older grout from below will start coming before the newer one and will take out the new one as well. Regrout would be the best. Same idea as recaulking
Pay a professional, time is money and tile/grout work is a hassle
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