Hi mum, I don’t have personal experience with changing citizenship, but from what I know it’s usually quite a big decision and not something very fast or simple, especially if changing from Singapore citizenship to another country. There are usually residency requirements, paperwork, approvals and also things to consider long term like children’s status, schooling, CPF and future plans. If this is something you’re seriously considering, I would really suggest checking with the official immigration authorities or speaking to someone experienced in citizenship matters because every family situation can be quite different.
Honestly I don't have much firsthand experience with this, so I wouldn't want to give you the wrong info and cause you more headache. I'd suggest going straight to ICA for the Singapore side of things, and maybe the Malaysian High Commission if Malaysia is where you're looking at. It's quite a big decision especially with kids involved, so getting it straight from the official source is really the safer way to go.