Some Christians seem very ready to sign up to the 'authority of Scripture'; some are as quick to question this concept, quickly bringing up problems with it (notably around the interpretation of Scripture) and/or pointing out other relevant authorities to consider (such as reason, tradition, experience, culture, creeds).
Somehow a spirit of fear rather than faith seems to creep into these matters. I sense that the 'authority of Scripture' is feared by some Christians because it has become associated in their minds with abusive power. Conversely, 'interpretation of Scripture' seems to be feared by others because it is associated with undermining the authority of Scripture.
The call to faith around Scripture is primarily to faith in God. The authority of Scripture is, in fact, the authority of the God whose revelation is conveyed to us through Scripture, the God, that is, who is revealed to be Love. To recognize the authority of Scripture is simply to recognize the generous love of God which gifts to us the knowledge of God we need for life to be lived in abundance.
The interpretation of Scripture is the interpretation of the revelation of the God who is truth and light: it cannot be other than clear and straightforward to understand! In fact God's promise to us, the Holy Spirit, is the gift of the One who both inspires and illuminates Scripture. Of course, there are many difficulties as we attempt to understand Scripture, which is a large document, composed of many words, stemming from a multiple set of generations and cultures far removed from our own. But if that is all we see in Scripture, we are likely to see problems and not solutions! The God of Scripture is the God for whom nothing is impossible.
One key to accepting the authority of Scripture and interpreting Scripture is placing our faith in God rather than in Scripture, keeping our eyes fixed on The Author and Interpreter of Scripture rather than on Scripture itself.