Help a newbie

Hello folks! I got an uke yesterday but have some serious problem about it. Firstly I need to tell you that I know scales and tuning from my guitar. My uke is a really cheap one (about 18 USD or so).
So the problem is that it is tuned well and stays in the right tune for an average time. But the chords sound detuned when I play them. I tried to compare the intervals of my uke with the correct piano intervals and found a problem. When the string is in tune, the other notes in that string (barre) won't be in tune. There isn't half interval between the original string and the first barre. However when I match the first barre to it's correct note, the other ones (2nd, 3rd etc.) match with each other, the only problem is with the string itself.
So what do you suggest me to do, use an capo? return the uke and get a new one? Anything else? Please let me know.
Best

The problem is called intonation. We have 2 other threads going now on intonation. If the ukulele is tuned correctly is the barre chord going flat or sharp?

To be honest expecting an $18 ukulele to have correct intonation is a little too much.

Anthony

It's going sharp. I'm considering getting a better one. Thanks for your help

Well if the intonation is going sharp try my matchstick fix. Slide a matchstick under the strings tightly up against the nut and see how it goes. Yes more expensive ukuleles are better but the intonation can still be out on ukuleles costing many hundreds of dollars.

Anthony