1. An information display apparatus comprising: a display; and a processor, wherein the processor is configured to: display text in a content area on the display in response to a user selection operation, and display a temporarily registered character string list and a searched entry word list in another area on the display other than the content area; temporarily register a character string which is included in the text displayed on the display in response to receiving a selection operation from the user that comprises selecting the character string in the text displayed on the display; update the displayed temporarily registered character string list to include the temporarily registered character string selected by the user; search an entry word corresponding to the temporarily registered character string from a dictionary in which each of a plurality of entry words is stored with corresponding explanatory information, in response to receiving a selection operation from the user that comprises selecting the temporarily registered character string in the displayed temporarily registered character string list; display on the display a first part of the explanatory information corresponding to the searched entry word as first explanatory information in the content area; change the display to display a second part of the explanatory information that is different from the first explanatory information in the content area, as second explanatory information, upon receiving a user operation; register the searched entry word in correspondence with a position of the second explanatory information of the searched entry word as a last displayed position, in accordance with receiving a user operation, and update the displayed searched entry word list to include the searched entry word; change the display from a state displaying the explanatory information in the content area to a state displaying the text in the content area, in accordance with receiving a user operation; and display, in the content area on the display, the explanatory information at the last displayed position of the second explanatory information of the registered searched entry word in response to receiving from the user an operation comprising selecting the registered searched entry word in the updated displayed searched entry word list.