Try different buds, the included buds on such a cheap iem are usually poor,
You could buy these below, I have no experience of this set but there appears to be plenty of choice
LunarCharm 54 pieces replacement silicone ear tips, 3 sizes headphone ear pads, replacement ear pads, compatible with most in-ear headphones, S/M/L : Amazon.co.uk: Electronics & Photo
www.amazon.co.uk
Or there’s the popular Dunu S&S set of eartips that I use on a few pairs of my iem’s, multipack shown below, they are decent and get a very good seal
Linsoul DUNU S&S Silicone Eartips S/M/L (3pairs) for Nozzle Diameter from 4mm-5.5mm for Stage Studio, for KZ ZS10 Pro, 7HZ Zero, Orchestra Lite, TANGZU Wan'er S.G IEM (S/M/L- Each Size 1 Pair): Amazon.co.uk: Musical Instruments & DJ
www.amazon.co.uk