Answer:
Step-by-step explanation:
First of all, 1:18. This depends on what Bible you look at. I think the King James version is just about as clear as they come. I take it to mean what KJV says. Here it is
"No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared him.
If you are a trinitarian, (I am not) this version does not help you very much, but it is clear. It means that no man (emphasis on man -- meaning those of us that are born on earth and were not created) has Seen God at any time. Then Jesus goes on to say that he has been at God's living bosom and he (Jesus) has come to declare who God is. If you put any more meaning that that on it, you are torturing language.
Now the second one is much harder, mainly because your grammar gets in the way. Your question means that you believe that Jesus and God are part of the trinity. Jesus in 1:18 claims only to be God's representative.
The Bible I use is the Good News Translation. Here's what it says about 5:37
The Father who sent me testifies on my behalf. You have never heard his voice, and you have never seen his form.
You have to understand clearly who Jesus is talking to. He is speaking to people who do not feel God (they have little or no Holy Spirit in them) and they cannot feel or see or know of God's presence. He is also talking about Baptism and the role of John the Baptist. This quotation is immensely complicated and cannot be read in isolation.
The fact that you think this upholds the trinity (that they should be able to see God by looking at Christ) is a widely held belief. You are certainly not alone in your beliefs. But you must read enough to find out who Jesus is talking to and about what. This particular verse is not saying what you think it is.