Season 1 & Season 2, it has the same look as the bumper card as it has been the case in future seasons, with "Daily" in the same font as "Double" & "Final", and "Double" in the same font as "Jeopardy!" Future Daily Double cards/graphics (usually) have both words in the same fonts. Font use for the "Daily" is Futura.
When a Daily Double is found, the camera zooms in and the Daily Double Logo flashes. It stops flashing when the clue is ready to appear. Originally, it was accompanied by a musical flourish when uncovered, but since late Season 1, it has been accompanied by a "laser" sound effect that has remained ever since. Since Season 2, when an Audio Daily Double is found, the camera faces to the player that selected it. Next, a little bit of music is played on some episodes and then the clue text appears below the player at the bottom of the screen.
These are the actual screenshots of the images shown above.
Starting with the third season, when a Daily Double is found, it's Daily Double Logo flips around as it zooms in. Back then after the player makes a wager, the clue text zooms in to replace the Daily Double Logo. But when an audio Daily Double is found, the clue is placed below the player that selected it at the bottom of the screen. Then the music plays for about 15 seconds.
Season 6 Daily Double with blue grid background, white text and red arrows pointing up and down. From here to Season 7, Gill Sans returns, appearing both in the original and condensed versions; it is also used in Super Jeopardy!
Season 6 Daily Double with Red Text, blue arrows on a very interesting background which go up and down just like the previous picture.
Season 8 was the last season to have the clue text zoom in to cover the Daily Double Logo. It's also the last season for the clue text to appear below the player that selected Audio Daily Double clues at the bottom of the screen. In 1992, the Daily Double Logo is now seen next to the player that selected it on the left side of the screen. But, after the clue is read out it doesn't disappear. It would disappear when the camera would point either at Alex Trebek or to all 3 players. But since September 1992, the clue does disappear after the clue is read.
Season 8a, starting here up until Season 9, the font used is Horatio Bold
Season 8a (Alternative version)
Season 8 Audio Daily Double
Season 9; same font letters from Season 8 with a bright red background.
Alternative version of the Season 9 Daily Double card without the brightness.
Season 9 Audio Daily Double on a rough wall background.
Alternate Season 9 Daily Double intertitle used for the College Championship and the Tournament of Champions; font used is Optima.
Season 10, font used is Helvetica
Both "Audio" And "Video" have this font which is Brush Script
Season 11-13 Same red background from Season 10 with yellow letters over blue globe; font used is Bau
Season 10-12, used for Celebrity Jeopardy!; font used is Bau
Sharing the same font with "Audio"; the font used for "Video" is Brush Script.