How to fill cracks in walls

I have the same problem round the windows that I had replaced. I’ve tried to do some filling myself but did pay someone to do some of it (annoyingly he got paint on the wall and I had no touch up paint and also hadn’t put frog tape on the window frames).He did say that some cracks need that squirty stuff because it needs to expand when the weather warms up although I would have used polyfilla.Did you perhaps not gauge enough out around the cracks before you filled them?

Thanks, MayBee70. I didn't fill them before.
Some decorators have done the job better than others and the last one used a lot of shortcuts, I suspect.
What do you use to gauge out the cracks, please? The stuff that expands after filling sounds excellent. I'll look into that.

I don’t really like the expanding stuff to be honest. It’s easier to paint over polyfilla.

I’ve attached the link for what I used last time, it’s advanced Polyfilla, which is lightweight and designed for deep cracks. I found it a lot easier to use than the normal Polyfilla, which I always struggle to get absolutely flush to the wall.
www.polycell.co.uk/en/products/polycell-advanced-polyfilla

Thanks Casdon. That looks just what I need.

We use this, the red one. Tape carefully first.

www.sealantsupplies.co.uk/product-category/foams-fillers/expanding-foam/?srsltid=AfmBOooCYg7qYSwrV8GI76wQCsWt_f_8EZwF2i0JjWwulyrTHKnBzy9N

Decorators Caulk from any DIY store. You will need the squirting gun as well. Make sure the gap is clean squirt the caulk in and after a couple of minutes, whilst it’s still pliable smooth over using a gloved finger. When it’s dry you can lightly sand and paint.

There are several very good You Tube videos showing you how to do this and recommending products.

Thanks to everyone who had replied so far. I will look into all the recommendations.

J52

Decorators Caulk from any DIY store. You will need the squirting gun as well. Make sure the gap is clean squirt the caulk in and after a couple of minutes, whilst it’s still pliable smooth over using a gloved finger. When it’s dry you can lightly sand and paint.

This is correct, however, I now use a dampened sponge to smooth it over because it works better than a finger.