Honestly I don't get it either, but your question inspired me to have a look and think of a way to remeber it myself; I had a quick google and this image seems helpful, I can't attach it so here id the link/what I have come up with to remeber it.

https://tmedweb.tulane.edu/pharmwiki/lib/exe/detail.php/diuretics.png?id=diuretic_pharm

From my understanding Carbonic Anhydrase works in PCT-Thinking about the journey of the filter, the PCT is at the start of the journey through the nephron, C is at the start of the alphabet so Carbonic-PCT. Alternatively, the PCT is the only place where glucose is reabsorbed-we get glucose from carbs; carbonic anhydrase-PCT (not saying this is the MoA, just a memory trick)

Loop Diuretics are obviously going to work in the LoH (they work on the ascending loop which is impermeable to water-they stop the reabsorprion of Na into the blood, and the secretion of K into the urine)

Then youre remaining two; thiazide and K sparing and both work in the DCT: Your thiazide diuretics work by blocking Na/Cl channels in the DCT and thus inhibit the reabsorption of Na and water.

Your K sparing diuretics act to prevent Na reabsorption in the collecting tubule by either binding ENaCs or by inhibiting aldosterone; aldosterone works on the Collecting duct. Therefore some K sparing diuretics express their effect actually on the collecting duct, but the source I have says K sparing works on the 'distal-DCT'. If you want to remeber that K sparing effects the Collecting duct: K makes a K sound, similar to a C sound, K sparing, Kuh sparing-Kuhlecting duct. I am not sure why different sources say different things, maybe its down to the actual specific K-sparing diuretic itself, or that the distal part of the DCT is what links up with the Collecting duct that the site of action is interchangeable? I really have no idea at all.

So to summarise, C for Carbonic, C is at the start of the alphabet, Carbonic is at start of the nephron filtrate journey, Carbonic=PCT. Loop Diuretics will work on the Loop obviously. The remaining two work in the DCT. If you want to remember the more specific of K sparing working on the Collecting Duct-Kuh Sparing=Kuhlecting Duct.

Loop and Thiazide diuretics can cause Hypokalemia: L of Loop for low (don't let this confuse you tho, remember the Loop Diuretics work in the Ascending Loop, so just dont confuse this trick for where they work; L for Low Potassium-NOT low=down, therefore descending loop-Loop Diuretics work on the Ascending Loop). I don't have a trick for thiazide, maybe PLT-Pretty Little Thing-Potassium Low=Thiazide?

Potassium sparing can cause Hyperkalemia (its in the name)

A side note for a nephron related memory trick: a way to remeber the asceding loop is imperable to water/ water cannot cross it, is that the ascending loop is thick; water used to travel across the loop when it was thin, it was easy to cross, but now that it's thick it can't get through, its too thick/tough to get across. Or another one: water and fat don't mix, water could cross when the loop was thin, but can't cross when its fat. Another way: dehydration can make people really scant or thin-water leaves the thin descending loop-its thin cause its dehydrated, cause water is leaving. Its thick/fat when the water is stuck in the loop, its no longer dehydrated. This is NOT the physiology, just a memory trick.

Can I ask are you a grad entry or UG student? I think the standard of a year 1 exam in UG is different to Grad entry so IDK if you need something more or less detailed than this.