I don’t keep track of my weight so I could be wrong here, but more/less than last time wouldn’t be very helpful as your weight can vary by the day. You need a trend over weeks to really see what’s going on. I definitely wouldn’t use pen/paper as it’s just too much data to organize and graph, but excel would be a reasonable alternative.
I don’t know what you want man. I like automating stuff so I don’t have to worry about remembering as much.