All these miracles is literally “these many signs.” (For “sign” as a mighty work, see 2.11.)

In their presence is more literally “before them.” In some languages in their presence is best rendered “with them looking on” or “while they were themselves seeing what was happening.”

They did not believe is the rendering of most translations, though New American Bible has “they refused to believe” and Goodspeed and New English Bible have “they would not believe in him.” In light of verse 40, these may be legitimate renderings, but it seems best to use a more neutral verb, such as “did not.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .