Seems like meter may be an older unit, no longer in production. Autozone appears to carry new replacement 3306N.
https://www.amazon.com/dp/B001J4RIDI/
https://www.autozone.com/test-scan-a...eter/64471_0_0
Link to original page on YouTube.
What you have should be more than enough for basic measurements of voltage and resistance. We're not exactly building spaceships here! Resistance readings jumping around on bulbs is troubling.
1. How are you connecting to bulbs to measure?
2. what resistance-range do you have meter set to?
3. what resistance reading do you get when test-leads are touching?
4. what resistance reading do you get when test-leads are not touching?