yesterday left my work pc on as usual with firefox open on google page (NOT SIGNED IN)..I never sign in went home, during the night I heard a new song on the radio but missed the title and the artist, I used shazam on android to find the name of the song, shazam found it, I opened youtube (NOT SIGNED IN) application on android and listened to the new song that I never heard before then I started listening to other suggested videos....

next day I go to work, unlock my windows session and find 3 open tabs with the same name of the sangs I listened on my android I check if i am signed in in anyway and it show i am not signed in, firefox sync is not set and never was set on this computer or my android... how it can be that this happened ?