How to switch between different Rust versions and toolchains using rustup?

Hi! I recently started learning Rust and ran into a problem: I have several projects that require different compiler versions. One project uses stable Rust 1.60, and another uses nightly because it needs experimental features. I installed Rust via `rustup`, but I don't understand how to properly switch between these toolchains. Here's what I'm doing: when I go into the folder with a project that requires nightly, I manually run `rustup default nightly`, but then when I switch to another project, I need to change the default toolchain again. This is very inconvenient, and I'm afraid of breaking something. I've heard there are `rust-toolchain.toml` or `rust-toolchain` files, but I don't fully understand how to use them. I also tried running `rustup run nightly cargo build`, but it seems a bit