535 not marking fish

Hi all, been lurking here awhile and really considering upgrading to a 798 from my 535 that came with the boat.
I have fishID turned on and set at max sensitivity but I can’t seem to get the unit to mark any fish. I have a transducer mounted on the trolling motor and another in the bilge area for thru hull. When I put the unit on the bow for trolling, I get a lot of interference so I only use it for finding depth. The interference is random, sometimes it’ll be clear and shows the bottom only, and sometimes it’ll show a bunch of lines in random locations continuously. It does this with or without the trolling motor plugged in or running. I cut the ducer cord and shortened it so there’d be less secondary magnetic field interference but no dice. I digress…
My main issue is that I can’t seem to discern a fish from floating matter. It seems to show slight arches, I know it’s not always possible to get perfect arches. It’ll show arches but the fishID won’t be triggered, i’ve got it set to show all sizes. I toss my line down and get nothing. I guess I don’t even know if they’re fish or not. I would see arches and reverse the trolling motor and the arches would be gone, everytime.
I seem to be able to see weeds very well since they cloud up the screen.

Other things I’ve tried, turned off auto max depth to 50 ft, lower range to 50 ft, high chart speed, and probably a bunch of other settings.
Is this unit too old to discriminate between fish and debris?
I’m going to try and get a screenshot next time I’m out but I just thought I’d ask to see if this thing is just junk and shouldn’t waste my time or not.

Use binoculars.Look for other boats catching fish and move in on them,less frustration.

Good first post.

Find the auto reset on the unit and go back tot he factory settings.

Welcome
my nephews unit did the same thing. Marked bottom but nothing much else. Reset did nothing. Bought new transducer with same results. Bought Elite 7 on sale and marks lots of fish,weeds,bait etc. He wishes he had done it sooner.

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Use binoculars.Look for other boats catching fish and move in on them,less frustration.

Good first post.

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That’s amazingly effective, the people always seem crabby though…

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Use binoculars.Look for other boats catching fish and move in on them,less frustration.

Good first post.

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What if…there aren’t any other boats?

Bought a 998 yesterday so we’ll see if my old unit was being erratic.

Nice unit, that should do the trick.