Ohms law's statement
Please correct me if I am wrong or like if I define the correct statement. &quot;Current is directly proportional to voltage if resistance kept constant&quot; V=IR

We can find the resistance of a conductor by measuring the voltage across it and the current through it, and taking the ratio.
The statement above therefore is a tautology, a constant proportionality between voltage and current means exactly the same thing as a constant resistance.

Ohms law is only applied when resistance kept constant or not? Am I right or not?

In its original meaning, Ohm's Law should only be applied to 'Ohmic' materials, that is, materials that exhibit a constant resistance. Materials with non-constant resistance are by definition 'non-ohmic'.
However, common meaning appears to have shifted a little, and we now seem to talk about applying 'Ohms Law' to the process of computing the voltage from the current or vice versa given a figure for resistance. Often, resistance is more or less constant, but there are things like filament lamps, whose resistance typically varies over a 10:1 ratio from cold to hot, and thermistors, which are very non-constant.
Given that so few people today recognise the distinction of 'Ohmic' meaning constant resistance, anybody trying to insist on would probably be thought of as a pedant. I prefer to talk about the behaviour of the material, is its V/I ratio dependent on the voltage, on the temperature, on anything else? And then I go and use the term 'Ohms Law' in the present, loose, sense.