I use simplenote. It's plain text, syncs, is multi platform, and is free. https://simplenote.com/

I find that images, etc, clutter things, and that for me plain text works the best - my snippets are usually code - and it handles that well. I often use urls to link out.

In terms of remembering things - I find typing it out helps, but writing it with pen and paper helps more... and finally the most help is to review your notes. As long as you review soon after taking them, the format almost doesn't matter.