Wakarimasen = I could not understand (polite) Wakaranai = i could not understand (a bit rude) Wakarimashite = I see ( or i understand)

Wakarimasen: Explaining your status as "You are not undestanding it" Wakaranai: Just explaining your feeling like "I cannot understand it" WakarimashitA: "Oh, I got it!"

Wakarimasen わかりません　＝ i don't understand ( More Polite ) Wakaranai わからない　＝ i don't understand Wakarimashita　わかりました　＝ understood