Is gear oil supposed to be white when changed from outboard engine

Was gear oil milky, or water and oil separate? Do you use in fresh or salt water?

I suppose you mean the oil in the Trim system...

Lift the engine all the way up,
Place the jackstand to keep the engine fully up.
You'll see a plastic plug in the center cylinder.
Unscrew that plug. ( There can be some pressure, take care of your eyes!)
Fill with ATF-oil till the level is at the bottom of the plug hole.
Screw the plug back in.
Lower the engine.
Done!

There are videos all over YouTube that cover this subject quite nicely.
winterizing an outboard motor YouTube

is it 4 stroke or 2 stroke?

I usually do cars and trucks, but if you are getting an electronic beep, you might go online and refer to an engine Manual for what you own. You may have a low oil lockout for the crankcase on a 4 cycle or a low oil cutoff alert for a 2 cycle with an automatic oil feed mixer. Some transition of inboard-outboard technology to outboards can include tilt lockout so that you can not start up in gear. Most prevent the starter from turning, but could keep the engine from firing if they want to wire it that way. With the "beeps" it would seem to be a Code.

Hello, is it the external shift handle you want to replace?

Then you'll have to remove the engine block from the driveshaft housing.
To do so: Drain the engine oil.
Disconnect the throttle cable from the carburettor.
Disconnect the start-in-gear cable from the recoil starter housing.
Disconnect the fuel lead at the fuel connector
Disconnect the choke puller at the carburettor.
Disconnect the white and black wire from the stop button at the engine-block and engine wires.
Remove 6 bolts holding the engine-block to the driveshaft housing.
Lift the engineblock.
The shift lever is fixed with a M6 bolt in the front-top of the driveshaft housing. You'll need a new gasket, Part Num 803508-9

Good luck!

Every year or once every 50 hours. Use only fully synthetic gear oil. Fill from the bottom drain screw until oil comes out upper screw. Put in upper screw and then lower screw.

to change fluid,take out the bottom plug;should be a flat head screwdriver fitting place something to catch old fluid under the lower unit,then take out top plug,it should drain right out... then from the bottom... fill the lower unit till fluid starts to come out of the top hole then put bottom plug back in, then top plug back in and your good to go..when you have the plugs out check the seals on the plugs and replace if needed...that will insure no water can get in..as far as the fuel mixture you can google that info

You can get aftermarket seals and such as long as they match the old ones. You can also use Lubriplate 105 in the gearcase instead of the High Performance gear oil. The 105 is alot heavier and will not hurt it. It will actually get you more life out of a tired gearcase. The main thing that you want to remember is that you have to put the engine in fwd gear and then disconnect the shift linkage. That is so that when you are reinstalling the gearcase you can turn the prop by hand to line up the splines in the powerhead. after you disconnect the shift linkage you should be able to just slide it right out. Make sure that you replace the seal under the waterpump base also.

If its a 2 stroke, there is no oil to change, if its a 4 stroke, you can pump the oil out with a small diameter tube pump.Depending on the motor, you can get it through the dipstick or the fill opening. If you need to change the gear oil, there is no way to change it while in the water. Stop by a marine supply store and get some oil absorbsion pads (diapers) in case you happen to spill any oil into the water