The sky appearing to meet the ocean has to do with perspective, not with curvature. The human eye can only detail a limited resolution, which is why boats will appear to "disappear over the horizon". That they can be brought back into view with a telescope demonstrates that this is everything to do with perspective and the limited resolution of the eye, rather than imaginary curvature that cannot be detected.
Either you believe scripture is divinely inspired (God-breathed) or not. I believe the former. If you believe the latter, it is likely fruitless to argue based on scripture, as you may argue anything you disagree with is tainted by human error.
As stated previously, the burden of proof is on heliocentrists to demonstrate valid evidence for their theory, not for Flat Earthers to disprove it. If you can't accept the authority of scripture on this subject and won't understand the basic principles of science and logic, we have an unreconcilable mismatch in worldview and philosophy, and therefore will never come to an agreement on the subject.
Only according to Heliocentric theory. Even if Heliocentric theory were true, God stopping the sun revolving around the galactic centre would have absolutely nothing to do with the sun appearing to remain in place in the sky in Joshua 10. Which makes me question your motive for even bringing it up. Obfuscation, perhaps?