Why do blue screens keep happening?

Blue screens leave traces.
Put the times they happened next to what changed around then, and the list of likely causes gets short.

What it does

Shows when and how often blue screens and unexpected shutdowns happened.

Checks the link with graphics driver resets and outdated drivers.

Lists recent driver, Windows Update and program changes in time order.

Tells you what to try in order, such as updating a driver or rolling back a recent install.

I had one blue screen. Should I worry?

One is fine to watch. If it repeats within a few days, check the records and recent changes.

Can it check for bad memory?

You can run Windows Memory Diagnostic straight from the toolbox. The test needs a restart.

After installing, click the tray icon and your first diagnosis is already done.
Every change runs only after you confirm it, and can be undone.