Ukulele strings can last a long time, but changing them will make a huge difference in sound SO why put it off. It really isn’t that hard, but if you are slow like me it might take a little while. Do it while you watch TV, rest or something.
There are different ways that strings attach to the bridge – a knot, a ball or inserted and looped as above. If your strings are like the above, be sure to start with the G, then the C, E and finally the A so that you can tuck the ends of the strings under/behind the next string and so that the ends will face the bottom of the uke body – you are much less likely to catch the downward pointing strings than if pointed up or were cut (similar to the photo).